OCA / OCP Practice Tests: Exam 1Z0-808 and Exam 1Z0-809

Java® SE 8 Programmer

Scott SelikoffJeanne Boyarsky

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To the new little bundle of joy my wife is carrying.— Scott

Remembering Einstein and CV in same year. Congrats 694!— Jeanne

AcknowledgmentsScott and Jeanne would like to thank numerous individuals for their contribution to thisbook. Thank you to David Clark for guiding us through the process and making the bookbetter in so many ways. Thank you to Janeice DelVecchio for being our technical editor aswe wrote this book. Janeice pointed out many subtle errors in addition to the big ones.And thank you to Elena Felder for being our technical proofreader and finding the errorsthat we managed to sneak by Janeice. This book also wouldn’t be possible without manypeople at Wiley, including Kenyon Brown, Rebecca Anderson, Judy Flynn, NancyCarrasco, and so many others.

Scott could not have reached this point without the help of a small army of people, led byhis perpetually understanding wife, Patti, the most wonderful mother their twindaughters, Olivia and Sophia, could ask for. Professors Johannes Gehrke and John H.Hubbard of Cornell University always believed in him and knew he would excel in hiscareer. Scott would like to extend his gratitude to his wonderfully patient co-authorJeanne, on this their third book. “I don’t know how she puts up with me, but I’m glad shedoes and thrilled at the quality of books we produce.” A big thanks to Matt Dalen, who hasbeen a great friend, sounding board, and caring father to the wonderfully sweet OliviaDalen. Joel McNary introduced Scott to CodeRanch.com and encouraged him to postregularly, a step that changed his life. Finally, Scott would like to thank his mother andretired teacher, Barbara Selikoff, for teaching him the value of education and his father,Mark Selikoff, for instilling in him the benefits of working hard.

Jeanne would personally like to thank everyone at CodeRanch.com who asked andresponded to OCA and OCP questions and comments about our first two books. Havingdialog with the readers made this book even stronger. Jeanne would like to thank themembers of FIRST robotics FRC team 694 in addition to FTC teams 310 and 479 for theirsupport. Your questions make it so she can never forget what new learners are thinking.Go StuyPulse! Jeanne would also like to thank Onur Otlu and Thomas Campos for thefeedback on some localization questions. Finally, Jeanne would like to thank Scott forbeing a great co-author and “not getting tired of me.”

Last but not least, both Scott and Jeanne would like to give a big thank you to the readersof our OCA 8 and OCP 8 books. Hearing from all of you who enjoyed the book and passedthe exam is a great feeling. We’d also like to thank those who pointed out errors andmade suggestions for improvements in our OCP book. As of December 2016, the top threewere Guillaume Bailly, Thalita Vergilio, and Sébastien Canonica. We also would like tothank Olivier Chalet, Mihaela Hetea, Peter Deak, Anton Shaikin, Ramya R, Tim Moroz,Aurelien Gamet, Javid Azimli, Salim Rahal, and Sander Wamelink.

http://CodeRanch.com


About the AuthorsScott Selikoff is a professional software consultant, author, and owner of SelikoffSolutions, LLC, which provides software development solutions to businesses in the tri-state New York City area. Skilled in a plethora of software languages and platforms, Scottspecializes in full-stack database-driven systems, cloud-based applications, and service-oriented architectures.

A native of Toms River, New Jersey, Scott achieved his Bachelor of Arts from CornellUniversity in Mathematics and Computer Science in 2002, after three years of study. In2003, he received his Masters of Engineering in Computer Science, also from CornellUniversity.

As someone with a deep love of education, Scott has always enjoyed teaching others newconcepts. He’s given lectures at Cornell University and Rutgers University, as well asconferences including the Server Side Java Symposium. Scott lives in New Jersey with hisloving wife, Patti; amazing twin toddler daughters, Olivia and Sophia; and two very playfuldogs, Webby and Georgette. You can find out more about Scott athttp://www.linkedin.com/in/selikoff.

Jeanne Boyarsky has worked as a Java developer for over 14 years at a bank in NewYork City where she develops, mentors, and conducts training. Besides being a seniormoderator at CodeRanch.com in her free time, she works on the forum’s code base.Jeanne also mentors the programming division of a FIRST robotics team, where sheworks with students just getting started with Java.

Jeanne got her Bachelor of Arts degree in 2002 in Computer Science and her Masters inComputer Information Technology in 2005. She enjoyed getting her Masters degree in anonline program while working full time. This was before online education was cool!Jeanne is also a Distinguished Toastmaster and a Scrum Master. You can find out moreabout Jeanne at https://coderanch.com/wiki/660334.

Scott and Jeanne are both moderators on the CodeRanch.com forums, and they can bereached there for questions and comments. They also co-author a technical blog calledDown Home Country Coding at http://www.selikoff.net.

In addition to this book, Scott and Jeanne are also the authors of OCA Oracle CertifiedAssociate Java SE 8 Programmer I Study Guide (Sybex, 2015) and OCP Oracle CertifiedProfessional Java SE 8 Programmer II Study Guide (Sybex, 2016). More recently, thesetwo books have been combined into the single release OCA / OCP Java SE 8 ProgrammerCertification Kit: Exam 1Z0-808 and Exam 1Z0-809 (Sybex 2016).

http://www.linkedin.com/in/selikoff


https://coderanch.com/wiki/660334


http://www.selikoff.net

ContentsAcknowledgmentsAbout the AuthorsIntroduction

Choosing an ExamWho Should Buy This BookHow This Book Is OrganizedReviewing Exam ChangesReady to Take the ExamNeed More Help Preparing?Bonus Contents

Part I OCAChapter 1 Java BasicsChapter 2 Working with Java Data TypesChapter 3 Using Operators and Decision ConstructsChapter 4 Creating and Using ArraysChapter 5 Using Loop ConstructsChapter 6 Working with Methods and EncapsulationChapter 7 Working with InheritanceChapter 8 Handling ExceptionsChapter 9 Working with Selected Classes from the Java APIChapter 10 OCA Practice Exam

Part II OCPChapter 11 Java Class DesignChapter 12 Advanced Java Class DesignChapter 13 Generics and CollectionsChapter 14 Lambda Built-in Functional InterfacesChapter 15 Java Stream APIChapter 16 Exceptions and AssertionsChapter 17 Use Java SE 8 Date/Time APIChapter 18 Java I/O FundamentalsChapter 19 Java File I/O (NIO.2)Chapter 20 Java ConcurrencyChapter 21 Building Database Applications with JDBC

kindle:embed:0006?mime=image/jpg

Chapter 22 LocalizationChapter 23 OCP Practice Exam

Appendix Answers to Review QuestionsChapter 1: Java BasicsChapter 2: Working with Java Data TypesChapter 3: Using Operators and Decision ConstructsChapter 4: Creating and Using ArraysChapter 5: Using Loop ConstructsChapter 6: Working with Methods and EncapsulationChapter 7: Working with InheritanceChapter 8: Handling ExceptionsChapter 9: Working with Selected Classes from the Java APIChapter 10: OCA Practice ExamChapter 11: Java Class DesignChapter 12: Advanced Java Class DesignChapter 13: Generics and CollectionsChapter 14: Lambda Built-in Functional InterfacesChapter 15: Java Stream APIChapter 16: Exceptions and AssertionsChapter 17: Use Java SE 8 Date/Time APIChapter 18: Java I/O FundamentalsChapter 19: Java File I/O (NIO.2)Chapter 20: Java ConcurrencyChapter 21: Building Database Applications with JDBCChapter 22: LocalizationChapter 23: OCP Practice Exam

AdvertEULA

List of TablesIntroduction

Table I.1

Table I.2

Table I.3

List of IllustrationIntroduction

Figure I.1 Exam prerequisites

IntroductionThis book is intended for those taking either the 1Z0-808 or 1Z0-809 Oracle JavaProgrammer exams as well as those who want to test their knowledge of Java 8. If you arenew to Java 8, we strongly recommend you start with a study guide to learn all of thefacets of the language and come back to this book once you are thinking of taking theexam.

We recommend the best-selling OCA Oracle Certified Associate Java SE 8 Programmer IStudy Guide and OCP Oracle Certified Professional Java SE 8 Programmer II StudyGuide, which we happen to be the authors of, to start in your studies. Regardless of whichstudy guide you are using to prepare, you can use this book to hone your skills, since it isbased on topics on the actual exams.

Unlike the questions in our study guides, which are designed to be harder than the realexam, the questions in this book mirror the exam format. All the questions in this booktell you how many answers are correct. They will say “Choose two” or “Choose three” ifmore than one answer is correct.

Throughout this book, we use the same set of assumptions that Oracle uses for its exams.In many cases, these assumptions are actually accounting for unintended omissions ortype-setting errors that Oracle is directing you to ignore when solving a question focusedon a particular exam objective. The assumptions are listed at http://education.oracle.comand listed here for your convenience:

Missing package and import statements: If sample code does not include package orimport statements, and the question does not explicitly refer to these missingstatements, then assume that all sample code is in the same package, and importstatements exist to support them.

No file or directory path names for classes: If a question does not state the filenames or directory locations of classes, then assume one of the following, whicheverwill enable the code to compile and run:

All classes are in one file.

Each class is contained in a separate file, and all files are in one directory.

Unintended line breaks: Sample code might have unintended line breaks. If yousee a line of code that looks like it has wrapped, and this creates a situation where thewrapping is significant (for example, a quoted String literal has wrapped), assumethat the wrapping is an extension of the same line, and the line does not contain ahard carriage return that would cause a compilation failure.

Code fragments: A code fragment is a small section of source code that is presentedwithout its context. Assume that all necessary supporting code exists, and that thesupporting environment fully supports the correct compilation and execution of the

http://education.oracle.com

code shown and its omitted environment.

Descriptive comments: Take descriptive comments, such as “setter and getters gohere,” at face value. Assume that correct code exists, compiles, and runs successfullyto create the described effect.

Choosing an ExamThe first step on the road to a Java certification is the Oracle Certified Associate 1Z0-808(OCA 8) exam. The material includes the basic day-to-day tools every Java developershould be familiar with. Once you have completed that exam, you can move on to themore difficult Oracle Certified Professional 1Z0-809 (OCP 8) exam. This includes everytopic on the first exam, along with many additional libraries and APIs that you may noteven be familiar with in your career, such as the Concurrency and NIO.2 APIs.

If you already hold a Java certification, you are eligible for an upgrade exam. Table I.1 andFigure I.1 show the various pathways to the OCP 8 certification title. This book will helpyou prepare for all four of the exams listed in the table.

TABLE I.1 Exams this book covers

ExamCode

Name Who should take

1Z0–808 Java Programmer I Everyone can take this exam.1Z0–809 Java Programmer II Those who pass the OCA 8 exam1Z0–810 Upgrade Java SE 7 to Java SE 8 OCP

ProgrammerHolders of an OCP 7 certification

1Z0–813 Upgrade to Java SE 8 OCP (Java SE 6 and allprior versions)

Holders of any of the followingcertifications:

SCJP/OCJP 6

SCJP/OCJP 5

SCJP 1.4

Any older SCJP certs

FIGURE I.1 Exam prerequisites

For the OCA exam, we recommend a study plan that uses our OCA Oracle CertifiedAssociated Java SE 8 Programmer I Study Guide along with Chapters 1 through 10 ofthis book. For the OCP exam, we recommend a study plan that uses our OCP OracleCertified Professional Java SE 8 Programmer II Study Guide along with Chapters 11through 23 of this book. That’s right, this book is actually two books in one! It assists youfor both the OCA and OCP exams.

Taking an Upgrade ExamThere are some subtle differences in how you should prepare if you are taking one of theupgrade exams. The good news is that if you currently hold a Java 7 OCP certification andare taking the 1Z0-810 upgrade exam, this book is all you need. While the exam containsa stronger focus on changes between Java 7 and Java 8, there aren’t any new topics notcovered with the existing OCP 7 material. This means you have the same study plan asthose taking the OCP for the first time.

On the other hand, if you are taking the 1Z0-813 upgrade exam and hold a Sun CertifiedJava Programmer (SCJP) or Oracle Certified Java Programmer (OCJP) title, then you willneed additional material. This upgrade inexplicably contains material that was in the Java7 OCP exam but removed from the Java 8 version, such as ReentrantLock andWatchService. For that, we have no explanation, although this does make the 1Z0-813arguably the most difficult of the three OCP exams because it requires knowingeverything from multiple versions of Java.

Have no fear! When we wrote our OCP Oracle Certified Professional Java SE 8Programmer II Study Guide, we added a special 50-page appendix, Appendix C,“Upgrading from Java 6 or Earlier,” which covers the topics solely on the 1Z0-813 exam in

detail. If you are taking the 1Z0-813 exam, then after completing your studies with thisbook, you should consult our appendix in our OCP book or a Java 7 OCP study guide sothat you are prepared for all of the objectives.

Considering Other Study PathsIf you already hold a Java certification, you are not required to take an upgrade exam.Some developers find it more straightforward to start with the easier 1Z0-808 OCA examand then take the more challenging 1Z0-809 OCP exam. If you have no experience withJava 8 or just want more practice with it, taking the OCA exam followed by the OCP examcould be a better, albeit more expensive, learning experience than taking a single upgradeexam.

Also remember, if you do hold an old Java title and want to take an upgrade exam, youwill need to prove it before you will be granted the OCP 8 title, even if you pass theupgrade exam. This requires registering your older certification with Oracle’s CertViewsystem. We’ve heard feedback from some readers who had to search through old bindersand emails from over a decade ago to submit the proper documentation that allows themto be granted the OCP 8 title.

Finally, if you are new to Java certification, it is traditional to take the exams in order,with the OCA exam followed by the OCP exam. However, this is a not strict requirement.It is possible, although quite unorthodox, to take the harder OCP exam first and thencircle back to take the OCA exam. In this case, you’ll be granted both OCA and OCP titlesupon completion of the OCA exam. While we don’t recommend this strategy, Oracle doesallow it.

Who Should Buy This BookIf you are looking to take the OCA 8 exam (1Z0-808), then Chapters 1 through 10 of thisbook are for you. And once you’ve passed with flying colors, you’ll have the OCP materialhandy in case you decide to take the exam.

If you are looking to take the OCP 8 exam (1Z0-809) or OCP 8 upgrade exam (1Z0-810),then Chapters 1 through 23 of this book are for you. While Chapters 1 through 10 areprimarily focused on the OCA exam, the OCP exam is cumulative. We recommend youstart reviewing the OCA Chapters (1–10) to make sure you have a solid foundation andthen move on to the OCP Chapters (11–23) when you are ready.

As mentioned earlier, if you are looking to take the OCP 8 upgrade exam (1Z0-813), thisbook will still help for the vast majority of topics. You will need to supplement this bookwith a Java 7 study guide or use Appendix C in our OCP book, which focuses on theprecise topics on the 1Z0-813 exam that you need to know.

Regardless of which exam you plan to take, make sure to always keep your study guidehandy. This book is about honing your knowledge of Java 8, while your study guide isabout building it.

How This Book Is OrganizedFor this book, we decided to write two books in one, divided into Parts I and II. Part Iincludes Chapters 1 through 10, with nine objective-based chapters for each of the OCAexam objective sets followed by a simulated OCA practice exam. Part II encompassesChapters 11 through 23, with 12 objective-based chapters for each of the OCP examobjective sets followed by a simulated OCP practice exam.

There are some subtle differences between the objective-based chapters and practiceexam chapters that you should be aware of while reading this book.

Using the Objective-Based ChaptersWe designed the structure and style of each question in the objective-based chapters toreflect a more positive learning experience, allowing you to spend less time on eachquestion but covering a broader level of material. For example, you may see twoquestions that look similar within a chapter but contain a subtle difference that hasdrastic implications on whether or not the code compiles, or what output it produces.

Each question in the objective-based chapters has exactly four options with only onecorrect answer. Just like the review questions in our study guide, these questions aredesigned so that you can answer them many times. While these questions may be easierthan exam questions, they will reinforce concepts if you keep taking them on a topic youdon’t feel strongly on.

In our study guides, we often group related topics into chapters. For example, if/thenstatements and loops, which are in separate Oracle objective sets, were presented in asingle chapter on Operators and Statements in our OCA book. In this book, we decided todesign our chapters solely around Oracle’s objectives so you can strengthen your skills.While you don’t need to read an entire study guide before using an objective-basedchapter in this book, you do need to study the relevant objectives. Tables I.2 and I.3 showwhat chapters you need to have read in our study guides as a minimum before practicingwith the questions in this book.

TABLE I.2 Reference in OCA study guide

Chapter in ThisBook

Objectives OCA Study GuideChapters

1 Java Basics 12 Working with Java Data Types 1, 33 Using Operators and Decision Constructs 2, 34 Creating and Using Arrays 35 Using Loop Constructs 26 Working with Methods and

Encapsulation4

7 Working with Inheritance 58 Handling Exceptions 69 Working with Selected Classes from the

Java API1, 3, 4

TABLE I.3 Reference in OCP study guide

Chapter in ThisBook

Objectives OCP Study GuideChapters

11 Java Class Design 1, 212 Advanced Java Class Design 1, 2, 313 Generics and Collections 3, 414 Lambda Built-in Functional

Interfaces2, 4

15 Java Stream API 3, 416 Exceptions and Assertions 617 Use Java SE 8 Date/Time API 518 Java I/O Fundamentals 819 Java File I/O (NIO.2) 920 Java Concurrency 721 Building Database Applications with

JDBC10

22 Localization 5

Using the Practice Exam ChaptersThis book contains two full-length practice exam chapters, with Chapter 10 being an 80-question OCA practice exam and Chapter 23 being an 85-question OCP practice exam.The questions in these two chapters are quite different from the objective-based chaptersin a number of important ways. These practice exam questions tend to be harder becausethey are designed to test your cumulative knowledge rather than reinforcing your existingskill set.

While all of the objective-based chapters had four options with only one correct answer,these questions have up to six options, with up to three correct answer choices. Based onfeedback from our first two books, we do indicate exactly how many answers are correctin the practice exam chapters, as is done on the real exam. Some readers thought the lackof knowing the correct number of answers made the questions too challenging forstudying.

Both practice exam chapters are designed to be taken within 150 minutes and have a

passing score of 65 percent. Remember not to take the practice exam until you feel ready.There are only so many practice exams available, so you don’t want to waste a freshattempt.

While an objective-based chapter can be completed over the course of a few days, thepractice exam chapters were designed to be completed in one sitting. You should trysimulating the exam experience as much as possible. This means setting aside two and ahalf hours, grabbing a whiteboard or scrap paper, and answering every question even ifyou aren’t sure of the answer. Remember, there is no penalty for guessing, and the moreincorrect answers you can eliminate the better.

Reviewing Exam ChangesOracle does change the number of questions, passing score, and time limit from time totime. In fact, the exam writers changed the number of OCA 8 questions from 77 to 80while this book was being written! Scott and Jeanne maintain a blog that tracks updatesto the real exams, as quickly as Oracle updates them:https://www.selikoff.net/jpt

We recommend you read this page before you take the real exam, in case any of theinformation since the time this book was published has changed. Although less common,Oracle does add, remove, or reword objectives. When this happens, we offer freesupplemental material on our website as blog entries.

https://www.selikoff.net/jpt

Ready to Take the ExamIf you can score above 80 percent consistently on all of the chapters related to the examyou want to take, including the simulated practice exam, then you are probably ready totake the real exam. Just remember there’s a big difference between taking a practice testat home and spending hundreds of dollars to take a real exam at a test center.

We could write an entire chapter on test taking skills and study tips. Oh wait, we did!Both our OCA 8 and OCP 8 books each contain an appendix chock-full of helpful tips andsuggestions that are designed to help you manage your time. They also include notes onhow to eliminate obviously wrong answers so that when you have to guess, you’rechoosing between two choices and not five.

Finally, although a lot of people are inclined to cram as much material as they can in thehours leading up to the exam, most studies have shown that this is a poor test-takingstrategy. The best thing we can recommend that you do before the exam is to get a goodnight’s rest!

Need More Help Preparing?Both of the authors are moderators at CodeRanch.com, a very large and activeprogramming forum that is very friendly toward Java beginners. It has separate forumsfor each of the exams:

OCA Forum: https://coderanch.com/f/117

OCP Forum: https://coderanch.com/f/24

If you don’t understand a question, even after reading the explanation, feel free to askabout it in one of those forums. You’ll get an answer from a knowledgeable Javaprogrammer. It might even be one of us.

Good luck on the exam and happy studies!


https://coderanch.com/f/117

https://coderanch.com/f/24

Bonus ContentsThis book has a web page that provides all the questions in this book using Wiley’sinteractive online test engine.

You can link to this from www.wiley.com/go/sybextestprep.

http://www.wiley.com/WileyCDA/WileyTitle/productCd-111936339X.html

PART IOCA

Chapter 1Java BasicsTHE OCA EXAM TOPICS COVERED IN THIS PRACTICE TEST INCLUDETHE FOLLOWING:

Java Basics

Define the scope of variables

Define the structure of a Java class

Create executable Java applications with a main method; run a Java program fromthe command line; produce console output

Import other Java packages to make them accessible in your code

Compare and contrast the features and components of Java such as: platformindependence, object orientation, encapsulation, etc.

1. Which of the following method signatures is a valid declaration of an entry point in aJava application?

A. public void main(String[] args)

B. public static void main()

C. private static void start(String[] mydata)

D. public static final void main(String[] mydata)

2. The following class diagram demonstrates the relationship between Gold and Silver,which extend the Metal class. Assume the attributes are all declared public. Whichstatement about the diagram is not true?

A. The diagram demonstrates platform independence in Java.

B. The diagram demonstrates object-oriented design in Java.

C. The Gold and Silver classes inherit weight and color attributes from the Metalclass.

D. Gold does not inherit the luster attribute.

3. What is the proper filename extension for a Java bytecode compiled file?

A. .java

B. .bytecode

C. .class

D. .dll

4. Given that a Date class exists in both the java.util and java.sql packages, what is theresult of compiling the following class?

1: import java.util.*;2: import java.sql.*;3: public class BirthdayManager {

4: private Date rob = new Date();5: private java.util.Date sharon = new java.util.Date();6: }

A. The code does not compile because of lines 1 and 2.

B. The code does not compile because of line 4.

C. The code does not compile because of line 5.

D. The code compiles without issue.

5. Which of the following is not a facet of traditional object-oriented programminglanguages?

A. Objects are grouped as procedures, separate from the data they act on.

B. An object can take many forms via casting.

C. An object can hold data, referred to as attributes.

D. An object can perform actions, via methods.

6. Which variables have a scope limited to a method?

A. Interface variables

B. Class variables

C. Instance variables

D. Local variables

7. Which package is imported into every Java class by default?

A. java.util

B. java.lang

C. system.lang

D. java.system

8. Which of the following is not a valid code comment in Java?

A. // Add 5 to the result

B. /*** TODO: Fix bug 12312 ***/

C. # Add configuration value

D. /* Read file from system ****/

9. Which statement about a valid .java file is true?

A. It can only contain one class declaration.

B. It can contain one public class declaration and one public interface definition.

C. It must define at least one public class.

D. It may define at most one public class.

10. Given the following application, fill in the missing values in the table starting from thetop and going downward.

package competition;public class Robot { static String weight = "A lot"; /* default */ double ageMonths = 5, ageDays = 2; private static boolean success = true; public void main(String[] args) { final String retries = "1"; // P1 }}

Variable Type Number of Variables Accessible at P1Class _______Instance _______Local _______

A. 2, 0, 1

B. 2, 2, 1

C. 1, 0, 1

D. 0, 2, 1

11. Which statement about import statements is true?

A. The class will not compile if it contains unused import statements.

B. Unused import statements can be removed from the class without causing a classto become unable to be compiled.

C. The class will not compile if a duplicate import statement is present.

D. If a class contains an import statement for a class used in the program that cannotbe found, it can still compile.

12. What is the result of compiling and executing the following class?

1: public class ParkRanger {2: int birds = 10;3: public static void main(String[] data) {4: int trees = 5;5: System.out.print(trees+birds);6: }7: }

A. It does not compile.

B. It compiles but throws an exception at runtime.

C. It compiles and outputs 5.

D. It compiles and outputs 15.

13. Which statements about Java are true?

I. The java command can execute .java and .class files.

II. Java is not object oriented.

III. The javac command compiles directly into native machine code.

A. I only

B. III only

C. II and III

D. None are true.

14. Which of the following lines of code is not allowed as the first line of a Java class file?

A. import widget.*;

B. // Widget Manager

C. package sprockets;

D. int facilityNumber;

15. Which one of the following statements is true about using packages to organize yourcode in Java?

A. Every class is required to include a package declaration.

B. To create a new package, you need to add a package.init file to the directory.

C. Packages allow you to limit access to classes, methods, or data from classes outsidethe package.

D. It is not possible to restrict access to objects and methods within a package.

16. Given that the current directory is /user/home, with an application Java file in/user/home/Manager.java that uses the default package, which are the correctcommands to compile and run the application in Java?

A. javac Manager java Manager

B. javac Manager.java java Manager

C. javac Manager java Manager.class

D. javac Manager.java java Manager.class

17. Structuring a Java class such that only methods within the class can access itsinstance variables is referred to as _______.

A. platform independence

B. object orientation

C. inheritance

D. encapsulation

18. What is the output of the following code snippet?

String tree = "pine";int count = 0;if (tree.equals("pine")) { int height = 55; count = count + 1;}System.out.print(height + count);

A. 1

B. 55

C. 56

D. It does not compile.

19. Which of the following is true of a Java bytecode file?

A. It can be run on any computer with a compatible JVM.

B. It can only be executed on the same type of computer that it was created on.

C. It can be easily read and modified in a standard text editor.

D. It requires the corresponding .java that created it to execute.

20. What is the correct character for terminating a statement in Java?

A. A colon (:)

B. An end-of-line character

C. A tab character

D. A semicolon (;)


1: public class Tolls {2: private static int yesterday = 1;3: int tomorrow = 10;4: public static void main(String[] args) {5: Tolls tolls = new Tolls();6: int today=20, tomorrow = 40;7: System.out.print(today + tolls.tomorrow + tolls.yesterday);8: }

9: }

A. The code does not compile due to line 6.

B. The code does not compile due to line 7.

C. 31

D. 61

22. Given the following class definition, which is the only line that does not contain acompilation error?

1: public ThisClassDoesNotCompile {2: double int count;3: void errors() {}4: static void private limit; }

A. Line 1

B. Line 2

C. Line 3

D. Line 4

23. Which of the following features allows a Java class to be run on a wide variety ofcomputers and devices?

A. Encapsulation

B. Object oriented

C. Inheritance

D. Platform independence

24. Which of the following is not a property of a JVM?

A. It prevents Java bytecode from being easily decoded/decompiled.

B. It supports platform independence.

C. It manages memory for the application.

D. It translates Java instructions to machine instructions.

25. Which of the following variables are always in scope for the entire program?

A. Package variables

B. Class variables

C. Instance variables

D. Local variables

26. Given the following wildcard import statements, which class would be included in theimport?

import television.actor.*;import movie.director.*;

A. television.actor.recurring.Marie

B. movie.directors.John

C. television.actor.Package

D. movie.NewRelease

27. Which is the correct order of statements for a Java class file?

A. import statements, package statement, class declaration

B. package statement, class declaration, import statement

C. class declaration, import statements, package declaration

D. package statement, import statements, class declaration

28. Given the following class definition, what is the maximum number of importstatements that can be discarded and still have the code compile? For this question,assume that the Blackhole class is defined only in the stars package.

package planetarium;import java.lang.*;import stars.*;import java.lang.Object;import stars.Blackhole; public class Observer { public void find(Blackhole blackhole) {}}

A. Zero

B. One

C. Two

D. Three

29. Given the following class definition, which command will cause the application tooutput the message White-tailed?

package forest;public class Deer { public static void main(String... deerParams) { System.out.print(theInput[2]); }}

A. java forest.Deer deer 5 "White-tailed deer"

B. java forest.Deer "White-tailed deer" deer 3

C. java forest.Deer Red deer White-tailed deer

D. java forest.Deer My "deer White-tailed"

30. Which of the following is a true statement?

A. The java command compiles a .java file into a .class file.

B. The javac command compiles a .java file into a .class file.

C. The java command compiles a .class file into a .java file.

D. The javac command compiles a .class file into a .java file.

31. Which of the following statements about Java is true?

A. Java is a procedural programming language.

B. Java allows method overloading.

C. Java allows operator overloading.

D. Java allows direct access to objects in memory.

32. Given the following code, what values inserted in order into the blank lines, allow thecode to compile?

_______agent;public _______Banker { private static _______getMaxWithdrawal() { return 10; }}

A. import, class, null

B. import, interface, void

C. package, int, int

D. package, class, long

33. What is the output of the following application?

public class Airplane { static int start = 2; final int end; public Airplane(int x) { x = 4; end = x; } public void fly(int distance) { System.out.print(end-start+" "); System.out.print(distance); } public static void main(String... start) { new Airplane(10).fly(5); }}

A. 2 5

B. 8 5

C. 6 5

D. The code does not compile.

34. What is one of the most important reasons that Java supports extending classes viainheritance?

A. Inheritance requires that a class that extends another class be in the same package.

B. The program must spend extra time/resources at runtime jumping throughmultiple layers of inheritance to determine precise methods and variables.

C. Method signature changes in parent classes may break subclasses that useoverloaded methods.

D. Developers minimize duplicate code in new classes by sharing code in a commonparent class.

35. Which of the following is a valid code comment in Java?

A. //////// Walk my dog

B. #! Go team!

C. / Process fails at runtime /

D. None of the above

36. Which of the following method signatures is not a valid declaration of an entry pointin a Java application?

A. public static void main(String... arguments)

B. public static void main(String arguments)

C. public static final void main(String[] arguments)

D. public static void main(String[] arguments)

37. Given the file Magnet.java below, which of the marked lines can you independentlyinsert the line public String color; into and still have the code compile?

// line a1public class Magnet { // line a2 public void attach() { // line a3 } // line a4}

A. a1 and a3

B. a2 and a4

C. a2, a3, and a4

D. a1, a2, a3, and a4

38. What is required to define a valid Java class file?

A. A class declaration

B. A package statement

C. At least one import statement

D. The public modifier

39. What is the proper filename extension for a Java source file?

A. .jav

B. .class

C. .source

D. .java

40. Given that a Math class exists in both the java.lang and pocket.complex packages,what is the result of compiling the following class?

1: package pocket;2: import pocket.complex.*;3: import java.util.*;4: public class Calculator {5: public static void main(String[] args) {6: System.out.print(Math.floor(5));7: }8: }

A. The code does not compile because of line 2.

B. The code does not compile because of line 3.

C. The code does not compile because of line 6.


41. Given a class that uses the following import statements, which class would not beautomatically accessible within the class without using its full package name?

import dog.*;import dog.puppy.*;

A. dog.puppy.female.KC

B. dog.puppy.Georgette

C. dog.Webby

D. java.lang.Object

42. _______is the technique of structuring programming data as a unit consisting ofattributes, with actions defined on the unit.

A. Encapsulation

B. Object orientation

C. Platform independence

D. Polymorphism

43. Given the following class definition, what is the maximum number of importstatements that can be discarded and still have the code compile? For this question,assume that the Broccoli class is in the food.vegetables package, and the Apple classis the food.fruit package.

package food;import food.vegetables.*;import food.fruit.*;import java.util.Date; public class Grocery { Apple a; Broccoli b; Date c;}

A. 0

B. 1

C. 2

D. 3

44. Given the following application, what is the expected output?

public class Keyboard { private boolean numLock = true; static boolean capLock = false; public static void main(String... shortcuts) { System.out.print(numLock+" "+capLock); }}

A. true false

B. false false

C. It does not compile.

D. It compiles but throws an exception at runtime.


public class RollerSkates { static int wheels = 1; int tracks = 5; public static void main(String[] arguments) {

RollerSkates s = new RollerSkates(); int feet=4, tracks = 15; System.out.print(feet + tracks + s.wheels); }}

A. The code does not compile.

B. 5

C. 10

D. 20


package sports;public class Bicycle { String color = "red"; private void printColor(String color) { color = "purple"; System.out.print(color); } public static void main(String[] rider) { new Bicycle().printColor("blue"); }}

A. red

B. purple

C. blue


47. Which statements about calling the compilation command javac and the executioncommand java are true?

I. java may use a period . to separate packages.

II. javac takes a .java file and returns a .class file.

III. java may use a slash (/) to separate packages.

A. I only

B. II only

C. I and II

D. I, II, and III

48. What is the result of compiling and executing the following application?

package forecast;public class Weather { private static boolean heatWave = true; public static void main() {

boolean heatWave = false; System.out.print(heatWave); }}

A. true

B. false


D. It compiles but throws an error at runtime.

49. Given the following class diagram, which Java implementation most closely matchesthis structure?

A. public class Book { public int numOfPages;

B. public class Book { public String getRating() {return null;} }

C. public class Book { public int numberOfPages;

public String getRating() {return null;} }

D. public class Book { void numberOfPages; }

50. Which statement about the JVM is true?

A. The JVM schedules garbage collection on a predictable schedule.

B. The JVM ensures that the application will always terminate.

C. The JVM requires a properly defined entry point method to execute theapplication.

D. A Java compiled code can be run on any computer.

Chapter 2Working with Java Data TypesTHE OCA EXAM TOPICS COVERED IN THIS PRACTICE TEST INCLUDETHE FOLLOWING:

Working with Java Data Types

Declare and initialize variables (including casting of primitive data types)

Differentiate between object reference variables and primitive variables

Know how to read or write to object fields

Explain an Object’s Lifecycle (creation, “dereference by reassignment” and garbagecollection)

Develop code that uses wrapper classes such as Boolean, Double, and Integer

1. Which of the following declarations does not compile?

A. double num1, int num2 = 0;

B. int num1, num2;

C. int num1, num2 = 0;

D. int num1 = 0, num2 = 0;

2. What is the output of the following?

public static void main(String... args) { String chair, table = "metal"; chair = chair + table; System.out.println(chair);}

A. metal

B. metalmetal

C. nullmetal


3. Which is correct about an instance variable of type String?

A. It defaults to an empty string.

B. It defaults to null.

C. It does not have a default value.

D. It will not compile without initializing on the declaration line.

4. Which of the following is not a valid variable name?

A. _blue

B. 2blue

C. blue$

D. Blue

5. Which of these class names best follows standard Java naming conventions?

A. fooBar

B. FooBar

C. FOO_BAR

D. F_o_o_B_a_r

6. How many of the following methods compile?

public String convert(int value) { return value.toString();

}public String convert(Integer value) { return value.toString();}public String convert(Object value) { return value.toString();}

A. None

B. One

C. Two

D. Three

7. Which of the following does not compile?

A. int num = 999;

B. int num = 9_9_9;

C. int num = _9_99;

D. None of the above; they all compile.

8. Which of the following is a wrapper class?

A. int

B. Int

C. Integer

D. Object

9. What is the result of running this code?

public class Values { integer a = Integer.valueOf("1"); public static void main(String[] nums) { integer a = Integer.valueOf("2"); integer b = Integer.valueOf("3"); System.out.println(a + b); }}

A. 4

B. 5

C. The code does not compile.

D. The code compiles but throws an exception at runtime.

10. Which best describes what the new keyword does?

A. Creates a copy of an existing object and treats it as a new one

B. Creates a new primitive

C. Instantiates a new object

D. Switches an object reference to a new one

11. Which is the first line to trigger a compiler error?

double d1 = 5f; // p1double d2 = 5.0; // p2float f1 = 5f; // p3float f2 = 5.0; // p4

A. p1

B. p2

C. p3

D. p4

12. Which of the following lists of primitive types are presented in order from smallest tolargest data type?

A. byte, char, float, double

B. byte, char, double, float

C. char, byte, float, double

D. char, double, float, bigint

13. Which of the following is not a valid order for elements in a class?

A. Constructor, instance variables, method names

B. Instance variables, constructor, method names

C. Method names, instance variables, constructor

D. None of the above: all orders are valid.

14. Which of the following lines contains a compiler error?

String title = "Weather"; // line x1int hot, double cold; // line x2System.out.println(hot + " " + title); // line x3

A. x1

B. x2

C. x3


15. How many instance initializers are in this code?

1: public class Bowling {

2: { System.out.println(); }3: public Bowling () {4: System.out.println();5: }6: static { System.out.println(); }7: { System.out.println(); }8: }

A. None

B. One

C. Two

D. Three

16. Of the types double, int, and short, how many could fill in the blank to have this codeoutput 0?

public static void main(String[] args) { _______defaultValue; System.out.println(defaultValue);}

A. None

B. One

C. Two

D. Three

17. What is true of the finalize() method?

A. It may be called zero or one times.

B. It may be called zero or more times.

C. It will be called exactly once.

D. It may be called one or more times.

18. Which of the following is not a wrapper class?

A. Double

B. Integer

C. Long

D. String

19. Suppose you have the following code. Which of the images best represents the state ofthe references right before the end of the main method, assuming garbage collectionhasn’t run?

1: public class Link {

2: private String name;3: private Link next;4: public Link(String name, Link next) {5: this.name = name;6: this.next = next;7: }8: public void setNext(Link next) {9: this.next = next;10: }11: public Link getNext() {12: return next;13: }14: public static void main(String... args) {15: Link link1 = new Link("x", null);16: Link link2 = new Link("y", link1);17: Link link3 = new Link("z", link2);18: link2.setNext(link3);19: link3.setNext(link2);20: link1 = null;21: link3 = null;22: }23: }

A. Option A

B. Option B

C. Option C

D. Option D

20. Which type can fill in the blank?

_______ pi = 3.14;

A. byte

B. float

C. double

D. short

21. What is the first line in the following code to not compile?

public static void main(String[] args) { int Integer = 0; // k1 Integer int = 0; // k2 Integer ++; // k3 int++; // k4}

A. k1

B. k2

C. k3

D. k4

22. Suppose foo is a reference to an instance of a class. Which of the following is not trueabout foo.bar?

A. bar is an instance variable.

B. bar is a local variable.

C. It can be used to read from bar.

D. It can be used to write to bar.

23. Which of the following is not a valid class declaration?

A. class building {}

B. class Cost$ {}

C. class 5MainSt {}

D. class _Outside {}

24. Which of the following can fill in the blanks to make this code compile?

_______d = new_______ (1_000_000_.00);

A. double, double

B. double, Double

C. Double, double


25. Which is correct about a local variable of type String?

A. It defaults to an empty string.

B. It defaults to null.

C. It does not have a default value.

D. It will not compile without initializing on the declaration line.

26. Of the types double, int, long, and short, how many could fill in the blank to have thiscode output 0?

static _______defaultValue; public static void main(String[] args) { System.out.println(defaultValue); }

A. One

B. Two

C. Three

D. Four

27. Which of the following is true about primitives?

A. You can call methods on a primitive.

B. You can convert a primitive to a wrapper class object simply by assigning it.

C. You can convert a wrapper class object to a primitive by calling valueOf().

D. You can store a primitive directly into an ArrayList.


Integer integer = new Integer(4);System.out.print(integer.byteValue()); System.out.print("-"); int i = new Integer(4);System.out.print(i.byteValue());

A. 4-0

B. 4-4



29. Given the following code, fill in the blank to have the code print bounce.

public class TennisBall { public TennisBall() { System.out.println("bounce"); } public static void main(String[] slam) {

_____________________ }}

A. TennisBall;

B. TennisBall();

C. new TennisBall;

D. new TennisBall();

30. Which of the following correctly assigns animal to both variables?

I. String cat = "animal", dog = "animal";

II. String cat = "animal"; dog = "animal";

III. String cat, dog = "animal";

IV. String cat, String dog = "animal";

A. I

B. I, II

C. I, III

D. I, II, III, IV

31. Which two primitives have wrapper classes that are not merely the name of theprimitive with an uppercase letter?

A. byte and char

B. byte and int

C. char and int


32. Which of the following is true about String instance variables?

A. They can be set to null.

B. They can never be set from outside the class they are defined in.

C. They can only be set in the constructor.

D. They can only be set once per run of the program.

33. Which statement is true about primitives?

A. Primitive types begin with a lowercase letter.

B. Primitive types can be set to null.

C. String is a primitive.

D. You can create your own primitive types.

34. How do you force garbage collection to occur at a certain point?

A. Call System.forceGc()

B. Call System.gc()

C. Call System.requireGc()


35. How many of the String objects are eligible for garbage collection right before the endof the main method?

public static void main(String[] fruits) { String fruit1 = new String("apple"); String fruit2 = new String("orange"); String fruit3 = new String("pear"); fruit3 = fruit1; fruit2 = fruit3; fruit1 = fruit2;}

A. None

B. One

C. Two

D. Three

36. Which of the following can fill in the blanks to make this code compile?

_______d = new_______ (1_000_000.00);

A. double, double

B. double, Double

C. Double, double


37. What does the following output?

1: public class InitOrder {2: public String first = "instance";3: public InitOrder() {4: first = "constructor";5: }6: { first = "block"; }7: public void print() {8: System.out.println(first);9: }10: public static void main(String... args) {11: new InitOrder().print(); 12: }13: }

A. block

B. constructor

C. instance


38. How many of the following lines compile?

int i = null;Integer in = null;String s = null;

A. None

B. One

C. Two

D. Three

39. Which pairs of statements can accurately fill in the blanks in this table?

Variable Type Can be called within the class from what type of methodInstance Blank 1:_______Static Blank 2: _______

A. Blank 1: an instance method only, Blank 2: a static method only

B. Blank 1: an instance or static method, Blank 2: a static method only

C. Blank 1: an instance method only, Blank 2: an instance or static method

D. Blank 1: an instance or static method, Blank 2: an instance or static method

40. Which of the following does not compile?

A. double num = 2.718;

B. double num = 2._718;

C. double num = 2.7_1_8;

D. None of the above; they all compile.

41. Which of the following lists of primitive numeric types is presented in order fromsmallest to largest data type?

A. byte, short, int, long

B. int, short, byte, long

C. short, byte, int, long

D. short, int, byte, long

42. Fill in the blank to make the code compile:

package animal;public class Cat { public String name; public static void main(String[] meow) { Cat cat = new Cat(); ______________ = "Sadie"; }}

A. cat.name

B. cat-name

C. cat.setName

D. cat[name]

43. Which of the following is the output of this code, assuming it runs to completion?

package store;public class Toy { public void play() { System.out.print("play-"); } public void finalizer() { System.out.print("clean-"); } public static void main(String[] fun) { Toy car = new Toy(); car.play(); System.gc(); Toy doll = new Toy(); doll.play(); }}

A. play-

B. play-play-

C. play-clean-play-

D. play-play-clean-clean-

44. Which is the most common way to fill in the blank to implement this method?

public class Penguin { private double beakLength; public static void setBeakLength(Penguin p, int b) { _____________________________ }}

A. p.beakLength = b;

B. p['beakLength'] = b;

C. p[beakLength] = b;


45. Fill in the blanks to indicate whether a primitive or wrapper class can be assignedwithout the compiler using the autoboxing feature.

_______first = Integer.parseInt("5"); _______second = Integer.valueOf("5");

A. int, int

B. int, Integer

C. Integer, int

D. Integer, Integer

46. How many objects are eligible for garbage collection right before the end of the mainmethod?

1: public class Person {2: public Person youngestChild;3:4: public static void main(String... args) {5: Person elena = new Person();6: Person diana = new Person();7: elena.youngestChild = diana;8: diana = null;9: Person zoe = new Person();10: elena.youngestChild = zoe;11: zoe = null;12: }13: }

A. None

B. One

C. Two

D. Three

47. Which is a valid constructor for this class?

public class TennisBall {}

A. public TennisBall static create() { return new TennisBall(); }

B. public TennisBall static newInstance() { return new TennisBall():}

C. public TennisBall() {}

D. public void TennisBall() {}

48. Which of the following is not a possible output of this code, assuming it runs tocompletion?

package store;public class Toy { public void play() { System.out.print("play-"); } public void finalize() { System.out.print("clean-"); } public static void main(String[] args) { Toy car = new Toy(); car.play(); System.gc(); Toy doll = new Toy(); doll.play(); }}

A. play-

B. play-play-

C. play-play-clean-

D. play-play-clean-clean-

49. Which converts a primitive to a wrapper class object without using autoboxing?

A. Call the asObject() method

B. Call the constructor of the wrapper class

C. Call the convertToObject() method

D. Call the toObject() method


package beach;public class Sand { public Sand() { System.out.print("a"); } public void Sand() { System.out.print("b"); } public void run() { new Sand(); Sand(); } public static void main(String... args) { new Sand().run(); }}

A. a

B. ab

C. aab


Chapter 3Using Operators and Decision ConstructsTHE OCA EXAM TOPICS COVERED IN THIS PRACTICE TEST INCLUDETHE FOLLOWING:

Using Operators and Decision Constructs

Use Java operators; use parentheses to override operator precedence

Test equality between Strings and other objects using == and equals()

Create if and if/else and ternary constructs

Use a switch statement

1. Which of the following variable types is not permitted in a switch statement?

A. String

B. double

C. int

D. char

2. What is the value of tip after executing the following code snippet?

int meal = 5;int tip = 2;int total = meal + (meal>6 ? ++tip : tip);

A. 1

B. 2

C. 3

D. 6


package registration;public class NameCheck { public static void main(String... data) { String john = "john"; String jon = new String(john); System.out.print((john==jon)+" "+(john.equals(jon))); }}

A. true true

B. true false

C. false true

D. false false


package planning;public class ThePlan { public static void main(String[] input) { int plan = 1; plan = plan++ + --plan; if(plan==1) { System.out.print("Plan A"); } else { if(plan==2) System.out.print("Plan B"); } else System.out.print("Plan C"); }}

A. Plan A

B. Plan B

C. Plan C


5. Which of the following statements about a default branch in a switch statement iscorrect?

A. All switch statements must include a default statement.

B. The default statement is required to be placed after all case statements.

C. Unlike a case statement, the default statement does not take a value.

D. A default statement can only be used when at least one case statement is present.

6. What is the value of thatNumber after the execution of the following code snippet?

long thatNumber = 5 >= 5 ? 1+2 : 1*1;if(++thatNumber < 4) thatNumber += 1;

A. 3

B. 4

C. 5

D. The answer cannot be determined until runtime.

7. Which statement immediately exits a switch statement, skipping all remaining case ordefault branches?

A. exit

B. break

C. goto

D. continue

8. Which statement about ternary expressions is true?

A. In some cases, both expressions to the right of the conditional operator in a ternaryexpression will be evaluated at runtime.

B. Ternary expressions require parentheses for proper evaluation.

C. The ternary expressions are a convenient replacement for an if-then-elsestatement.

D. Ternary expressions support int and boolean expressions for the left-mostoperand.


package voting;

1: public class Election {2: public void calculateResult(Integer candidateA, Integer candidateB) {3: boolean process = candidateA == null || candidateA.intValue() < 10;4: boolean value = candidateA && candidateB;5: System.out.print(process || value);6: }7: public static void main(String[] unused) {8: new Election().calculateResult(null,203);9: }10: }

A. true

B. false


D. The code compiles but throws a NullPointerException on line 3 at runtime.


package dinosaur;public class Park { public final static void main(String... arguments) { int pterodactyl = 6; long triceratops = 3; if(pterodactyl % 3 >= 1) triceratops++; triceratops--; System.out.print(triceratops); }}

A. 2

B. 3

C. 4


11. Which statement about if-then statements is true?

A. An if-then statement is required to have an else statement.

B. If the boolean test of an if-then statement evaluates to false, then the target clauseof the if-then statement will still be evaluated.

C. An if-then statement is required to cast an object.

D. An if-then statement can execute a single statement or a block {}.


package restaurant;public class Pieces { public static void main(String[] info) { int flair = 15;

if(flair >= 15 && flair < 37) { System.out.print("Not enough"); } if(flair==37) { System.out.print("Just right"); } else { System.out.print("Too many"); } }}

A. Not enough

B. Just right

C. Too many


13. Which statement about case statements of a switch statement is not true?

A. A case value can be final.

B. A case statement must be terminated with a break statement.

C. A case value can be a literal expression.

D. A case value must match the data type of the switch variable, or be able to bepromoted to that type.

14. Given the following truth table, which operator for the boolean expressions x and ycorresponds to this relationship?

x = true x = false

y = true true false

y = false false false

A. --

B. ++

C. ||

D. &&


int hops = 0;int jumps = 0;jumps = hops++;if(jumps) System.out.print("Jump!");else System.out.print("Hop!");

A. Jump!

B. Hop!



16. Fill in the blanks: The _____________ operator increases the value of a variable by1 and returns the new value, while the _____________ operator decreases thevalue of a variable by 1 and returns the original value.

A. pre-increment [++v], pre-decrement [--v]

B. pre-increment [++v], post-decrement [v--]

C. post-increment [v++], pre-decrement [--v]

D. post-increment [v++], post-decrement [v--]


package jungle;public class TheBigRace { public static void main(String[] in) { int tiger = 2; short lion = 3; long winner = lion+2*(tiger + lion); System.out.print(winner); } }

A. 11

B. 13

C. 25


18. Given the following code snippet, assuming dayOfWeek is an int, what variable type ofsaturday is not permitted?

final _________ saturday = 6;switch(dayOfWeek) { default: System.out.print("Another Weekday"); break; case saturday: System.out.print("Weekend!");}

A. byte

B. long

C. int


19. Given the following code snippet, what is the value of dinner after it is executed?

int time = 11;int day = 4;String dinner = time > 10 ? day ? "Takeout" : "Salad" : "Leftovers";

A. Takeout

B. Salad

C. The code does not compile but would compile if parentheses were added.



package recreation;public class Dancing { public static void main(String[] vars) { int leaders = 10 * (2 + (1 + 2 / 5); int followers = leaders * 2; System.out.print(leaders + followers < 10 ? "Too few" : "Too many"); }}

A. Too few

B. Too many


D. The code compiles but throws a division by zero error at runtime.


package schedule;public class PrintWeek { public static final void main(String[] days) { System.out.print(5 + 6 + "7" + 8 + 9); }}

A. 56789

B. 11789

C. 11717


22. Fill in the blanks: The______________ operator is used to find the differencebetween two numbers, while the______________ operator is used to find theremainder when one number is divided by another.

A. /, %

B. –, %

C. %, <

D. –, ||


package transporter;public class Rematerialize { public static void main(String[] input) { int dog = 11; int cat = 3; int partA = dog / cat; int partB = dog % cat; int newDog = partB + partA * cat; System.out.print(newDog); }}

A. 9

B. 11

C. 15



package dessert;public class IceCream { public final static void main(String... args) { int flavors = 30; int eaten = 0; switch(flavors) { case 30: eaten++; case 40: eaten+=2; default: eaten--; } System.out.print(eaten); }}

A. 1

B. 2

C. 3



package mode;public class Transportation { public static String travel(int distance) { return distance<1000 ? "train" : 10; } public static void main(String[] answer) { System.out.print(travel(500)); }

}

A. train

B. 10



26. Fill in the blanks: Given two non-null String objects with reference namesapples______________ and oranges, if apples oranges evaluates to true, thenapples______________ oranges must also evaluate to true.

A. ==, equals()

B. !=, equals()

C. equals(), ==

D. equals(), =!

27. For a given non-null String myTestVariable, what is the resulting value of executingthe statement myTestVariable.equals(null)?

A. true

B. false

C. The statement does not compile.

D. The statement compiles but will produce an exception when used at runtime.

28. How many 1s are outputted when the following application is compiled and run?

package city;public class Road { public static void main(String... in) { int intersections = 100; int streets = 200; if (intersections < 150) { System.out.print("1"); } else if (streets && intersections > 1000) { System.out.print("2"); } if (streets < 500) System.out.print("1"); else System.out.print("2"); }}

A. None

B. One

C. Two


29. Which statement about the logical operators & and && is true?

A. The & and && operators are interchangeable, always producing the same results atruntime.

B. The & operator always evaluates both operands, while the && operator may onlyevaluate the left operand.

C. Both expressions evaluate to true if either operand is true.

D. The & operator always evaluates both operands, while the && operator may onlyevaluate the right operand.


int x = 10, y = 5;boolean w = true, z = false;x = w ? y++ : y--;w = !z;System.out.print((x+y)+" "+(w ? 5 : 10));


B. 10 10

C. 11 5

D. 12 5


package bob;public class AreYouBob { public static void main(String[] unused) { String bob = new String("bob"); String notBob = bob; System.out.print((bob==notBob)+" "+(bob.equals(notBob))); }}

A. true true

B. true false

C. false true

D. false false

32. What is the value of 12 + 6 * 3 % (1 + 1) in Java?

A. 0

B. 12

C. 14


33. Given the following truth table, the boolean variables p and q, and the expression p ^q, what are the missing values in the truth table, starting with the first column?

p = true p = false

q = true false true

q = false

A. false and true

B. false and false

C. true and true

D. true and false

34. Which of the following is not a possible result of executing the following application?

public class ConditionallyLogical { public static void main(String... data) { if(data.length>=1 && (data[0].equals("sound") || data[0].equals ("logic")) && data.length<2) { System.out.print(data[0]); } }}

A. Nothing is printed.

B. sound is printed.

C. The application throws an exception at runtime.

D. logic is printed.

35. Fill in the blanks: The operators +,______________ ,______________,______________ , and ++ are listed in the same or increasing level of operatorprecedence.

A. *, --, /

B. %, -, *

C. /, *, %

D. *, -, /

36. What statement about the ^ operator is correct?

A. If one of the operands of ^ is true, then the result is always true.

B. There is a conditional form of the operator, denoted as ^^.

C. If both operands of ^ are true, the result is true.

D. The ^ operator can only be applied to boolean values.

37. Given the following Venn diagram and the variables, x, y, and z, which Java expressionmost closely represents the filled-in region of the diagram?

A. x || z

B. y || (y && z)

C. x || y

D. y && x

38. What variable type of red allows the following application to compile?

package tornado;public class Kansas { public static void main(String[] args) { int colorOfRainbow = 10; ________ red = 5; switch(colorOfRainbow) { default: System.out.print("Home"); break; case red: System.out.print("Away"); } }}

A. long

B. double

C. int


39. Which two operators would be used to test if a number is equal to or greater than 5.21but strictly less than 8.1?

A. > and <=

B. >= and >

C. < and >=

D. < and >


package transporter;public class TurtleVsHare { public static void main(String[] arguments) { int turtle = 10 * (2 + (3 + 2) / 5); int hare = turtle < 5 ? 10 : 25; System.out.print(turtle < hare ? "Hare wins!" : "Turtle wins!"); }}

A. Hare wins!

B. Turtle wins!


D. The code compiles but throws a division by zero error at runtime.


public class CountEntries { public static int getResult(int threshold) { return threshold > 5 ? 1 : 0; } public static final void main(String[] days) { System.out.print(getResult(5)+getResult(1) +getResult(0)+getResult(2)+""); }}

A. 0

B. 1

C. 0000

D. 1000


package yoyo;public class TestGame { public String runTest(boolean spinner, boolean roller) { if(spinner = roller) return "up"; else return roller ? "down" : "middle"; } public static final void main(String pieces[]) { final TestGame tester = new TestGame(); System.out.println(tester.runTest(false,true)); }}

A. up

B. middle

C. down


43. Fill in the blanks: The______________ operator is true if either of the operandsare true, while the______________ operator flips a boolean value.

A. +, -

B. &&, !

C. |, -

D. ||, !

44. Given the following code snippet, what is the value of movieRating after it is executed?

int characters = 5;int story = 3;double movieRating = characters <= 4 ? 3 : story>1 ? 2 : 1;

A. 2.0

B. 3.0

C. The code does not compile but would compile if parentheses were added.


45. Fill in the blanks: A switch statement can have______________ case statementsand______________ default statements.

A. at most one, at least one

B. any number of, at most one

C. at least one, any number of

D. at least one, at most one

46. Which of the following is not a possible result of executing the following application?

public class OutsideLogic { public static void main(String... weather) { System.out.print(weather[0]!=null && weather[0].equals("sunny") && !false ? "Go Outside" : "Stay Inside"); }}

A. Nothing is printed.

B. The application throws an exception at runtime.

C. Go Outside is printed.

D. Stay Inside is printed.

47. What is the value of (5 + (!2 + 8) * 3 - 3 % 2)/2 in Java?

A. 2

B. 11

C. 16


48. Given the following truth table, the boolean variables w and z, and the expression w ||z, what are the missing values in the truth table, starting with the first row?

w = true w = false

z = true true

z = false false

A. false and false

B. true and false

C. true and true

D. false and true

49. Fill in the blanks: The operators –,______________ ,______________,______________ , and % are listed in the same or increasing level of operatorprecedence.

A. +, /, *

B. --, -, *

C. ++, /, *

D. *, ++, %


public class Baby { public static String play(int toy, int age) { final String game; if(toy<2) game = age > 1 ? 1 : 10; // p1 else game = age > 3 ? "Ball" : "Swim"; // p2 return game; } public static void main(String[] variables) { System.out.print(play(5,2)); }

}

A. Ball

B. Swim

C. The code does not compile due to p1.

D. The code does not compile due to p2.

Chapter 4Creating and Using ArraysTHE OCA EXAM TOPICS COVERED IN THIS PRACTICE TEST INCLUDETHE FOLLOWING:

Creating and Using Arrays

Declare, instantiate, initialize and use a one-dimensional array

Declare, instantiate, initialize and use multi-dimensional arrays

1. What symbol is used for a varargs method parameter?

A. ..

B. ...

C. --

D. ---

2. Fill in the blank in the following code to get the first element from the varargsparameter.

public void toss (Frisbee... f) { Frisbee first = ____________;}

A. f

B. f[0]

C. f[1]


3. Which of the following are primitives?

int[] lowercase = new int[0];Integer[] uppercase = new Integer[0];

A. Only lowercase

B. Only uppercase

C. Bother lowercase and uppercase

D. Neither lowercase nor uppercase

4. How many of the following are legal declarations?

[]double lion;double[] tiger;double bear[];

A. None

B. One

C. Two

D. Three

5. Given the following two methods, which method call will not compile?

public void printStormName(String... names) { System.out.println(Arrays.toString(names));}public void printStormNames(String[] names) { System.out.println(Arrays.toString(names));

}

A. printStormName("Arlene");

B. printStormName(new String[] { "Bret" });

C. printStormNames("Cindy");

D. printStormNames(new String[] { "Don" });

6. How do you determine the number of elements in an array?

A. buses.length

B. buses.length()

C. buses.size

D. buses.size()

7. Which of the following create an empty two-dimensional array with dimensions 2×2?

A. int[][] blue = new int[2, 2];

B. int[][] blue = new int[2], [2];

C. int[][] blue = new int[2][2];

D. int[][] blue = new int[2 x 2];

8. How many lines does the following code output?

String[] days = new String[] { "Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday" };for (int i = 0; i < days.length; i++) System.out.println(days[i]);

A. Six

B. Seven



9. What are the names of the methods to do searching and sorting respectively onarrays?

A. Arrays.binarySearch() and Arrays.linearSort()

B. Arrays.binarySearch() and Arrays.sort()

C. Arrays.search() and Arrays.linearSort()

D. Arrays.search() and Arrays.sort()

10. What does this code output?

String[] nums = new String[] { "1", "9", "10" };Arrays.sort(nums);

System.out.println(Arrays.toString(nums));

A. [1, 9, 10]

B. [1, 10, 9]

C. [10, 1, 9]


11. Which of the following references the first and last element in a non-empty array?

A. trains[0] and trains[trains.length]

B. trains[0] and trains[trains.length - 1]

C. trains[1] and trains[trains.length]

D. trains[1] and trains[trains.length - 1]


String lion [] = new String[] {"lion"};String tiger [] = new String[1] {"tiger"};String bear [] = new String[] {};String ohMy [] = new String[0] {};

A. None

B. One

C. Two

D. Three


float[] lion = new float[];float[] tiger = new float[1];float[] bear = new[] float;float[] ohMy = new[1] float;

A. None

B. One

C. Two

D. Three

14. Which statement most accurately represents the relationship between searching andsorting with respect to the Arrays class?

A. If the array is not sorted, calling Arrays.binarySearch() will be accurate, butslower than if it were sorted.

B. The array does not need to be sorted before calling Arrays.binarySearch() to getan accurate result.

C. The array must be sorted before calling Arrays.binarySearch() to get an accurateresult.


15. Which is not a true statement about an array?

A. An array expands automatically when it is full.

B. An array is allowed to contain duplicate values.

C. An array understands the concept of ordered elements.

D. An array uses a zero index to reference the first element.

16. Which line of code causes an ArrayIndexOutOfBoundsException?

String[][] matrix = new String[1][2];matrix[0][0] = "Don't think you are, know you are."; // m1matrix[0][1] = "I'm trying to free your mind Neo"; // m2matrix[1][0] = "Is all around you "; // m3matrix[1][1] = "Why oh why didn't I take the BLUE pill?"; // m4

A. m1

B. m2

C. m3

D. m4


String[] os = new String[] { "Mac", "Linux", "Windows" };Arrays.sort(os);System.out.println(Arrays.binarySearch(os, "Mac"));

A. 0

B. 1

C. 2

D. The output is not defined.

18. Which is the first line to prevent this code from compiling and running without error?

char[][] ticTacToe = new char[3,3]; // r1ticTacToe[1][3] = 'X'; // r2ticTacToe[2][2] = 'X';ticTacToe[3][1] = 'X';System.out.println(ticTacToe.length + " in a row!"); // r3

A. Line r1

B. Line r2

C. Line r3


19. How many objects are created when running the following code?

Integer[] lotto = new Integer[4];lotto[0] = new Integer(1_000_000);lotto[1] = new Integer(999_999);

A. Two

B. Three

C. Four

D. Five


[][] String alpha;[] String beta;String[][] gamma;String[] delta[];String epsilon[][];

A. Two

B. Three

C. Four

D. Five

21. Which of the options in the graphic best represent the blocks variable?

char[][] blocks = new char[][] { { 'a', 'b', 'c' }, { 'd' }, { 'e', 'f' } };

A. Option A

B. Option B

C. Option C

D. Option D

22. What happens when calling the following method with a non-null and non-emptyarray?

public static void addStationName(String[] names) { names[names.length] = "Times Square";}

A. It adds an element to the array the value of which is Times Square.

B. It replaces the last element in the array with the value Times Square.


D. It throws an exception.


String[] days = new String[] { "Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday" };for (int i = 0; i < days.size(); i++) System.out.println(days[i]);

A. Six

B. Seven



24. How many dimensions does the array reference moreBools allow?

boolean[][][] bools, moreBools;

A. One dimension

B. Two dimensions

C. Three dimensions


25. What is a possible output of the following code?

String[] strings = new String[2];System.out.println(strings);

A. [null, null]

B. [,]

C. [Ljava.lang.String;@74a14482



char[][] ticTacToe = new char[3][3]; // r1ticTacToe[1][3] = 'X'; // r2ticTacToe[2][2] = 'X';ticTacToe[3][1] = 'X';System.out.println(ticTacToe.length + " in a row!"); // r3

A. Line r1

B. Line r2

C. Line r3


27. What is the result of running the following as java Copier?

package duplicate;public class Copier { public static void main(String... original) { String... copy = original; System.out.println(copy.length + " " + copy[0]); }}

A. 0

B. 0 followed by an exception

C. 1 followed by an exception


28. What is the result of running the following program?

1: package fun;2: public class Sudoku {3: static int[][] game = new int[6][6];4:5: public static void main(String[] args) {6: game[3][3] = 6;7: Object[] obj = game;8: obj[3] = "X";9: System.out.println(game[3][3]);10: }11: }

A. X

B. The code does not compile.

C. The code compiles but throws a NullPointerException at runtime.

D. The code compiles but throws a different exception at runtime.


String[] os = new String[] { "Mac", "Linux", "Windows" };Arrays.sort(os);System.out.println(Arrays.binarySearch(os, "RedHat"));

A. -1

B. -2

C. -3


30. What is the output of the following when run as java FirstName Wolfie?

public class FirstName { public static void main(String... names) { System.out.println(names[0]); }}

A. FirstName

B. Wolfie

C. The code throws an ArrayIndexOutOfBoundsException.

D. The code throws a NullPointerException.

31. What is the output of the following when run as java Count 1 2?

public class Count { public static void main(String target[]) { System.out.println(target.length); }}

A. 0

B. 1

C. 2


32. What is the output of the following when run as java unix.EchoFirst seed flower?

package unix;import java.util.*;public class EchoFirst { public static void main(String[] args) { String one = args[0]; Arrays.sort(args); int result = Arrays.binarySearch(args, one); System.out.println(result); }}

A. 0

B. 1



33. Which of these four array declarations produces a different array than the others?

A. int[][] nums = new int[2][1];

B. int[] nums[] = new int[2][1];

C. int[] nums[] = new int[][] { { 0 }, { 0 } };

D. int[] nums[] = new int[][] { { 0, 0 } };

34. How do you access the array element with the value of "z"?

A. dimensions["three"][2]

B. dimensions["three"][3]

C. dimensions[2][2]

D. dimensions[3][3]


String[] days = new String[] { "Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday" };for (int i = 1; i <= days.length; i++) System.out.println(days[i]);

A. Six

B. Seven



36. What is the output of the following when run as java FirstName Wolfie?

public class FirstName { public static void main(String... names) { System.out.println(names[1]); }}

A. FirstName

B. Wolfie




char[][] ticTacToe = new char[3][3]; // r1ticTacToe[0][0] = 'X'; // r2ticTacToe[1][1] = 'X';ticTacToe[2][2] = 'X';System.out.println(ticTacToe.length + " in a row!"); // r3

A. Line r1

B. Line r2

C. Line r3


38. What is the output of the following when run as java Count 1 2?

public class Count { public static void main(String target[]) { System.out.println(target.length()); }}

A. 0

B. 1

C. 2


39. How many dimensions does the array reference moreBools allow?

boolean[][] bools[], moreBools;

A. One dimension

B. Two dimensions

C. Three dimensions


40. What is the result of the following when called as java counting.Binary?

package counting;import java.util.*;public class Binary { public static void main(String... args) { Arrays.sort(args); System.out.println(Arrays.toString(args)); }}

A. null

B. []




String[] os = new String[] { "Mac", "Linux", "Windows" };System.out.println(Arrays.binarySearch(os, "Linux"));

A. 0

B. 1

C. 2



1: package fun;2: public class Sudoku {3: static int[][] game;4:5: public static void main(String[] args) {6: game[3][3] = 6;7: Object[] obj = game;8: game[3][3] = "X";9: System.out.println(game[3][3]);10: }11: }

A. X


C. The code compiles but throws a NullPointerException at runtime.

D. The code compiles but throws a different exception at runtime.


String[][] listing = new String[][] { { "Book" }, { "Game", "29.99" } };System.out.println(listing.length + " " + listing[0].length);

A. 2 1

B. 2 2



44. What is the output of the following when run as java FirstName?

public class FirstName { public static void main(String[] names) { System.out.println(names[0]);

}}

A. FirstName





String[] days = new String[] { "Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday" };for (int i = 1; i < days.length; i++) System.out.println(days[i]);

A. Six

B. Seven



46. What is the output of the following when run as java Count "1 2"?

public class Count { public static void main(String target[]) { System.out.println(target.length); }}

A. 0

B. 1

C. 2



String[] os = new String[] { "Linux", "Mac", "Windows" };System.out.println(Arrays.binarySearch(os, "Linux"));

A. 0

B. 1

C. 2


48. Which of the following statements are true?

I. You can always change a method signature from call(String[] arg) tocall(String... arg) without causing a compiler error in the calling code.

II. You can always change a method signature from call(String... arg) tocall(String[] arg) without causing a compiler error in the existing code.

A. I

B. II

C. Both I and II

D. Neither I nor II

49. Which of these four array references can point to an array that is different from theothers?

A. int[][][][] nums1a, nums1b;

B. int[][][] nums2a[], nums2b;

C. int[][] nums3a[][], nums3b[][];

D. int[] nums4a[][][], numbs4b[][][];

50. What is the output of the following when run as java unix.EchoFirst seed flower?

package unix;import java.util.*;public class EchoFirst { public static void main(String[] args) { Arrays.sort(args); String result = Arrays.binarySearch(args, args[0]); System.out.println(result); }}

A. 0

B. 1



Chapter 5Using Loop ConstructsTHE OCA EXAM TOPICS COVERED IN THIS PRACTICE TEST INCLUDETHE FOLLOWING:

Using Loop Constructs

Create and use while loops

Create and use for loops including the enhanced for loop

Create and use do/while loops

Compare loop constructs

Use break and continue

1. Which type of loop is best known for its boolean condition that controls entry to theloop?

A. do-while loop

B. for (traditional)

C. for-each

D. while

2. Which type of loop is best known for using an index or counter?

A. do-while loop


C. for-each

D. while

3. Which type of loop is guaranteed to have the body execute at least once?

A. do-while loop


C. for-each

D. while

4. Which of the following can loop through an array without referring to the elements byindex?

A. do-while loop


C. for-each

D. while

5. What keyword is used to end the current loop iteration and proceed execution with thenext iteration of that loop?

A. break

B. continue

C. end

D. skip

6. What keyword is used to proceed with execution immediately after a loop?

A. break

B. continue

C. end

D. skip

7. Which type of loop has three segments within parentheses?

A. do-while loop


C. for-each

D. while

8. Which of the following statements is/are true?

I. A traditional for loop can iterate through an array starting from index 0.

II. A traditional for loop can iterate through an array starting from the end.

A. Only I

B. Only II

C. Both statements

D. Neither statement

9. Which of the following statements is/are true?

I. A for-each loop can iterate through an array starting from index 0.

II. A for-each loop can iterate through an array starting from the end.

A. Only I

B. Only II

C. Both statements

D. Neither statement

10. Which type of loop has a boolean condition that is first checked after a single iterationthrough the loop?

A. do-while loop


C. for-each

D. while

11. What does the following code output?

int singer = 0;while (singer) System.out.println(singer++);

A. 0


C. The loops complete with no output.

D. This is an infinite loop.


List<String> drinks = Arrays.asList("can", "cup");for (int container = drinks.size() - 1; container >= 0; container ) System.out.print(drinks.get(container) + ",");

A. can,cup,

B. cup,can,




public static void main(String[] args) { List<String> bottles = Arrays.asList("glass", "plastic"); for (int type = 0; type < bottles.size();) { System.out.print(bottles.get(type) + ","); break; } System.out.print("end");}

A. glass,end

B. glass,plastic,end




String letters = "";while (letters.length() != 2) letters+="a";System.out.println(letters);

A. aa

B. aaa

C. The loops complete with no output.


15. What is the result of the following when run with java peregrine.TimeLoopSeptember 3 1940?

package peregrine;

public class TimeLoop { public static void main(String[] args) { for (int i = args.length; i>=0; i++) System.out.println("args"); }}

A. args

B. argsargs



16. What is the output of the following code?

package chicago;public class Loop { private static int count; private static String[] stops = new String[] { "Washington", "Monroe", "Jackson", "LaSalle" }; public static void main(String[] args) { while (count < stops.length) { if (stops[count++].length() < 8) { break; } } System.out.println(count); }}

A. 1

B. 2

C. 4


17. What is the result of the following code?

do { int count = 0; do { count++; } while (count < 2); break;} while (true);System.out.println(count);

A. 2

B. 3



18. Which of the following segments of a for loop can be left blank?

for (segmentA; segmentB; segmentC) {}

A. segmentA

B. segmentB

C. segmentC

D. All of the above

19. How many of the loop types (while, do while, traditional for, and enhanced for) allowyou to write code that creates an infinite loop?

A. One

B. Two

C. Three

D. Four


List<String> drinks = Arrays.asList("can", "cup");for (int container = 0; container < drinks.size(); container++) System.out.print(drinks.get(container) + ",");

A. can,cup,

B. cup,can,



21. What happens when running the following code?

do ( System.out.println("helium");) while (false);

A. It completes successfully without output.

B. It outputs helium once.

C. It keeps outputting helium.


22. Which of the following is equivalent to this code snippet given an array of Stringobjects?

for (int i=0; i<fun.length; i++) System.out.println(fun[i]);

A. for (String f = fun) System.out.println(f);

B. for (String f : fun) System.out.println(f);

C. for (String = fun) System.out.println(it);


23. How many of these statements can be inserted after the println to have the code flowfollow the arrow in this diagram?

break;break letters;break numbers;

A. None

B. One

C. Two

D. Three

24. Using the diagram in the previous question, how many of these statements can beinserted after the println to have the code flow follow the arrow in the diagram?

continue;continue letters;continue numbers;

A. None

B. One

C. Two

D. Three


int singer = 0;while (singer > 0) System.out.println(singer++);

A. 0


C. The loops completes with no output.


26. Which of the following types is taxis not allowed to be in order for this code tocompile?

for (Object obj : taxis) {}

A. ArrayList<Integer>

B. int[]

C. StringBuilder

D. All of these are allowed.


boolean balloonInflated = false;do { if (!balloonInflated) { balloonInflated = true; System.out.print("inflate-"); }} while (! balloonInflated);System.out.println("done");

A. done

B. inflate-done




String letters = "";while (letters.length() != 3) letters+="ab";System.out.println(letters);

A. ab

B. abab

C. The loop completes with no output.


29. What describes the order in which the three expressions appear in a for loop?

A. boolean conditional, initialization expression, update statement

B. initialization expression, boolean conditional, update statement

C. initialization expression, update statement, boolean conditional


30. What is the result of the following?

int count = 10;List<Character> chars = new ArrayList<>();do { chars.add('a'); for (Character x : chars) count -=1;} while (count > 0);System.out.println(chars.size());

A. 3

B. 4




int k = 0;for (int i = 10; i > 0; i ) { while (i > 3) i = 3; k += 1;}System.out.println(k);

A. 1

B. 2

C. 3

D. 4

32. Which of the following is equivalent to this code snippet given an array of Stringobjects?

for (int i=fun.length-1; i>=0; i ) System.out.println(fun[i]);

A. for (String f = fun) System.out.println(f);

B. for (String f : fun) System.out.println(f);

C. for (String f fun) System.out.println(it);



public static void main(String[] args) { List<String> bottles = Arrays.asList("glass", "plastic"); for (int type = 0; type < bottles.size();) System.out.print(bottles.get(type) + ","); break;

System.out.print("end");}

A. glass,end

B. glass,plastic,end




String[] nycTourLoops = new String[] { "Downtown", "Uptown", "Brooklyn" };String[] times = new String[] { "Day", "Night" };for (int i = 0, j = 0; i < nycTourLoops.length && j < times.length; i++; j++){ System.out.print(nycTourLoops[i] + " " + times[j] + "-");}

A. Downtown Day-

B. Downtown Day-Uptown Night-



35. What is the result of the following when run with java peregrine.TimeLoopSeptember 3 1940?

package peregrine;public class TimeLoop { public static void main(String[] args) { for (int i = args.length; i>=0; i ) System.out.println(args[i]); }}

A. September

B. 1940




public class Shoelaces { public static void main(String[] args) { String tie = null; while (tie == null) tie = "shoelace"; System.out.print(tie); }}

A. null

B. shoelace

C. shoelaceshoelace


37. The following code outputs a single letter x. What happens if you remove lines 25 and28?

23: String race = "";24: loop:25: do {26: race += "x";27: break loop;28: } while (true);29: System.out.println(race);

A. It prints an empty string.

B. It still outputs a single letter x.

C. It no longer compiles.

D. It becomes an infinite loop.

38. What is the output of the following code?

package chicago;public class Loop { private static int count; private static String[] stops = new String[] { "Washington", "Monroe", "Jackson", "LaSalle" }; public static void main(String[] args) { while (count < stops.length) { if (stops[count++].length() < 8) { continue; } } System.out.println(count); }}

A. 1

B. 2

C. 4



StringBuilder builder = new StringBuilder();String str = new String("Leaves growing");do { System.out.println(str);

} while (builder);System.out.println(builder);

A. Leaves growing

B. This is an infinite loop.




6: int count = 0;7: do {8: do {9: count++;10: } while (count < 2);11: break;12: } while (true);13: System.out.println(count);

A. 2

B. 3



41. Fill in the blank so this code compiles and does not cause an infinite loop.

t: while (true) { f: while(true) { _____________ }}

A. break;

B. break f;

C. break t;



String[] nycTourLoops = new String[] { "Downtown", "Uptown", "Brooklyn" };String[] times = new String[] { "Day", "Night" };for (int i = 0, j = 0; i < nycTourLoops.length && j < times.length; i++, j++){ System.out.print(nycTourLoops[i] + " " + times[j] + "-");}

A. Downtown Day-

B. Downtown Day-Uptown Night-




import java.util.*;public class Exams { public static void main(String[] args) { List<String> exams = Arrays.asList("OCA", "OCP"); for (String e1 : exams) for (String e2 : exams) System.out.println(e1 + " " + e2); }}

A. One

B. Four



44. Which of the following best describes the flow of execution in this for loop if betaalways returns false?

for (alpha; beta; gamma) { delta;}

A. alpha

B. alpha, beta

C. alpha, beta, gamma


45. Which of the following best describes the flow of execution in this for loop if the loopbody is run exactly once?

for (alpha; beta; gamma) { delta;}

A. alpha, delta, gamma, beta

B. alpha, beta, delta, gamma, beta

C. alpha, delta, gamma, alpha, beta

D. alpha, beta, delta, gamma, alpha, beta

46. Which of the following iterates a different number of times than the others?

A. for (int k=0; k < 5; k++) {}

B. for (int k=1; k <= 5; k++) {}

C. int k=0; do { } while(k++ < 5)

D. int k=0; while (k++ < 5) {}


public class Shoelaces { public static void main(String[] args) { String tie = null; while (tie == null); tie = "shoelace"; System.out.print(tie); }}

A. null

B. shoelace

C. shoelaceshoelace



12: int result = 8;13: for: while (result > 7) {14: result++;15: do {16: result--;17: } while (result > 5);18: break for;19: }20: System.out.println(result);

A. 5

B. 8




boolean baloonInflated = false;do { if (!baloonInflated) { baloonInflated = true; System.out.print("inflate-"); }} while (baloonInflated);System.out.println("done");

A. done

B. inflate-done



50. Which of the following can fill in the blank to have the code compile successfully?

package nyc;public class TouristBus { public static void main(String... args) { String[] nycTourLoops = new String[] { "Downtown", "Uptown", "Brooklyn" }; String[] times = new String[] { "Day", "Night" }; for (_____________ i < 1; i++, j++) System.out.println(nycTourLoops[i] + " " + times[j]); }}

A. int i=0; j=0;

B. int i=0, j=0;

C. int i=0; int j=0;

D. int i=0, int j=0;

Chapter 6Working with Methods and EncapsulationTHE OCA EXAM TOPICS COVERED IN THIS PRACTICE TEST INCLUDE THEFOLLOWING:

Working with Methods and Encapsulation

Create methods with arguments and return values; including overloaded methods

Apply the static keyword to methods and fields

Create and overload constructors; differentiate between default and user definedconstructors

Apply access modifiers

Apply encapsulation principles to a class

Determine the effect upon object references and primitive values when they arepassed into methods that change the values

1. Fill in the blanks: The____________ access modifier allows access to everything

the ____________access modifier does and more.

A. package-private, protected

B. protected, public

C. protected, package-private

D. private, package-private

2. What is the command to call one constructor from another constructor in the sameclass?

A. super()

B. this()

C. that()

D. construct()


package stocks;public class Bond { private static int price = 5; public boolean sell() { if(price<10) { price++; return true; } else if(price>=10) { return false; } } public static void main(String[] cash) { new Bond().sell(); new Bond().sell(); new Bond().sell(); System.out.print(price); }}

A. 5

B. 6

C. 8


4. What is true about the following program?

package figures;public class Dolls {

public void nested() { nested(2,true); } // g1 public int nested(int level, boolean height) { return nested(level); } public int nested(int level) { return level+1; }; // g2 public static void main(String[] outOfTheBox) { System.out.print(new Dolls().nested()); }}

A. It compiles successfully and prints 3 at runtime.

B. It does not compile because of line g1.

C. It does not compile because of line g2.

D. It does not compile for some other reason.

5. Fill in the blank: Java uses ___________ to send data into a method.

A. pass-by-null

B. pass-by-value

C. both pass-by-value and pass-by-reference

D. pass-by-reference

6. Which of the following is a valid JavaBean method signature?

A. public void getArrow()

B. public void setBow()

C. public void setRange(int range)

D. public String addTarget(String target)

7. Which of the following statements about calling this() in a constructor is not true?

A. If this() is used, it must be the first line of the constructor.

B. If super() and this() are both used in the same constructor, super() must appearon the line immediately after this().

C. If arguments are provided to this(), then there must be a constructor in the classable to take those arguments.

D. If the no-argument this() is called, then the class must explicitly implement theno-argument constructor.

8. Which of the following can fill in the blank to make the class compile?

package ai;public class Robot { ____________ compute() { return 10; }}

A. Public int

B. Long

C. void

D. private String

9. Fill in the blank: A ____________variable is always available to all instances of theclass.

A. public

B. local

C. static

D. instance

10. Which line of code, inserted at line p1, causes the application to print 5?

package games;public class Jump { private int rope = 1; protected boolean outside; public Jump() { // p1 outside = true; } public Jump(int rope) { this.rope = outside ? rope : rope+1; } public static void main(String[] bounce) { System.out.print(new Jump().rope); }}

A. this(4);

B. new Jump(4);

C. this(5);

D. rope = 4;

11. Which of the following statements is not true?

A. An instance of one class may access an instance of another class’s attributes if ithas a reference to the instance and the attributes are declared public.

B. An instance of one class may access package-private attributes in a parent class,provided the parent class is not in the same package.

C. Two instances of the same class may access each other’s private attributes.

D. An instance of one class may access an instance of another class’s attributes if bothclasses are located in the same package and marked protected.

12. Given the following class, what should be inserted into the two blanks to ensure the

class data is properly encapsulated?

package storage;public class Box { public String stuff; ____________String____________ () { return stuff; } public void setStuff(String stuff) { this.stuff = stuff; }}

A. public and getStuff

B. private and isStuff

C. public and setStuff


13. Which statement about a no-argument constructor is true?

A. The Java compiler will always insert a default no-argument constructor if you donot define a no-argument constructor in your class.

B. In order for a class to call super() in one of its constructors, its parent class mustexplicitly implement a no-argument constructor.

C. If a class extends another class that has only one constructor that takes a value,then the child class must explicitly declare at least one constructor.

D. A class may contain more than one no-argument constructor.

14. Which of the following method signatures does not contain a compiler error?

A. public void sing(String key, String... harmonies)

B. public void sing(int note, String... sound, int music)

C. public void sing(String... keys, String... pitches)

D. public void sing(String... notes, String melodies)

15. Given the following application, which diagram best represents the state of themySkier, mySpeed, and myName variables in the main() method after the call to theslalom() method?

package slopes;public class Ski { private int age = 18; private static void slalom(Ski racer, int[] speed, String name) { racer.age = 18; name = "Wendy"; speed = new int[1]; speed[0] = 11;

racer = null; } public static void main(String... mountain) { final Ski mySkier = new Ski(); mySkier.age = 16; final int[] mySpeed = new int[1]; final String myName = "Rosie"; slalom(mySkier,mySpeed,myName); }}

A.

B.

C.

D.

16. Given the class below, which method signature could be successfully added to theclass as an overloaded version of the findAverage() method?

public class Calculations { public Integer findAverage(int sum) { return sum; }}

A. public Long findAverage(int sum)

B. public Long findAverage(int sum, int divisor)

C. public Integer average(int sum)

D. private void findAverage(int sum)

17. Which of the following is not a reason to use encapsulation when designing a class?

A. Promote usability by other developers.

B. Maintain class data integrity of data elements.

C. Prevent users from modifying the internal attributes of a class.

D. Increase concurrency and improve performance.

18. Which of the following data types can be modified after they are passed to a method asan argument?

A. int[]

B. String

C. long

D. boolean

19. What is the best way to call the following method from another class in the samepackage, assuming the class using the method does not have any static imports?

package useful;public class MathHelper { public static int roundValue(double d) { // Implementation omitted }}

A. MathHelper:roundValue(5.92)

B. MathHelper.roundValue(3.1)

C. roundValue(4.1)

D. useful.MathHelper.roundValue(65.3)

20. Given a method with one of the following return types, which data type prevents thereturn statement from being used within the method?

A. byte

B. String

C. void


21. How many final modifiers would need to be removed for this application to compile?

package end;public final class Games { public final static int finish(final int score) { final int win = 3; final int result = score++ < 5 ? 2 : win; return result+=win; } public static void main(final String[] v) { System.out.print(finish(Integer.parseInt(v[0]))); }}

A. None

B. One

C. Two

D. The code will not compile regardless of the number of final modifiers that areremoved.

22. Fill in the blanks: ____________is used to call a constructor in the parent class,while ____________is used to reference a member of the parent class.

A. super and this()

B. super and super()

C. super() and this

D. super() and super

23. Given the following method signature, which classes can call it?

void run(String government)

A. Classes in other packages

B. Classes in the same package

C. Subclasses in a different package

D. All classes

24. Which statement(s) about the following class would help to properly encapsulate thedata in the class?

package shield;public class Protect { private String material; protected int strength; public int getStrength() { return strength; } public void setStrength(int strength) { this.strength = strength; }}

I. Change the access modifier of strength to private.

II. Add a getter method for material.

III. Add a setter method for material.

A. I

B. II and III

C. I, II, and III

D. None, the data in the class is already encapsulated.

25. Which of the following is a valid method name in Java?

A. Go_$Outside$2()

B. have-Fun()

C. new()

D. 9enjoyTheWeather()

26. Which of the following lines of code can be inserted in the line below that would allowthe class to compile?

package farm;public class Coop { public final int static getNumberOfChickens() { // INSERT CODE HERE }}

A. return 3.0;

B. return 5L;

C. return 10;


27. Which of the following is a true statement about passing data to a method?

A. A change made to a primitive value passed to a method is reflected in the callingmethod.

B. A change made to the data within an object passed to a method is reflected in thecalling method.

C. Reassigning an object reference passed to a method is reflected in the callingmethod.

D. A change made to a boolean value passed to a method is reflected in the callingmethod.

28. What is a possible output of the following application?

package wrap;public class Gift { private final Object contents; protected Object getContents() { return contents; } protected void setContents(Object contents) { this.contents = contents; } public void showPresent() { System.out.print("Your gift: "+contents); } public static void main(String[] treats) { Gift gift = new Gift(); gift.setContents(gift); gift.showPresent(); }}

A. Your gift: wrap.Gift@29ca2745

B. Your gift: Your gift:


D. It compiles but throws an exception at runtime.

29. Which of the following is a valid JavaBean method prefix?

A. is

B. gimme

C. request

D. put

30. Given the following two classes, each in a different package, which line inserted belowallows the second class to compile?

package clothes;public class Store { public static String getClothes() { return "dress"; }} package wardrobe;// INSERT CODE HEREpublic class Closet { public void borrow() { System.out.print("Borrowing clothes: "+getClothes()); }}

A. static import clothes.Store.getClothes;

B. import clothes.Store.*;

C. import static clothes.Store.getClothes;

D. import static clothes.Store;

31. What access modifier is used to mark class members package-private?

A. private

B. default

C. protected


32. How many lines of the following program contain compilation errors?

package sky;public class Stars { private int inThe = 4; public void Stars() { super(); } public Stars(int inThe) { this.inThe = this.inThe; } public static void main(String[] endless) { System.out.print(new sky.Stars(2).inThe); }}

A. None

B. One

C. Two

D. Three

33. Which of the following statements is true?

A. An instance method is allowed to reference a static variable.

B. A static method is allowed to reference an instance variable.

C. A static initialization block is allowed to reference an instance variable.

D. A final static variable may be set in a constructor.

34. Given the following method declaration, which line can be inserted to make thecode compile?

public short calculateDistance(double lat1, double lon1, double lat2, double lon2) { // INSERT CODE HERE}

A. return new Integer(3);

B. return new Byte((byte)6);

C. return 5L;

D. return new Short(4).longValue();

35. Which of the following statements about overloaded methods are true?

I. Overloaded methods must have the same name.

II. Overloaded methods must have the same return type.

III. Overloaded methods must have a different list of parameters.

A. I

B. I and II

C. I and III

D. I, II, and III

36. How many lines of code would need to be removed for the following class to compile?

package work;public class Week { private static final String monday; String tuesday; final static wednesday = 3; final protected int thursday = 4;}

A. One

B. Two

C. Three

D. The code will not compile regardless of the number of lines removed.


package pet;public class Puppy { public static int wag = 5; // q1 public void Puppy(int wag) { // q2 this.wag = wag; } public static void main(String[] tail) { System.out.print(new Puppy(2).wag); // q3 }}

A. 2

B. It does not compile because of line q1.

C. It does not compile because of line q2.

D. It does not compile because of line q3.

38. Fill in the blanks: The ____________access modifier allows access to everythingthe ____________access modifier does and more.

A. public, private

B. private, package-private

C. package-private, protected

D. private, public


package ship;public class Phone { private int size; public Phone(int size) {this.size=size;} public static void sendHome(Phone p, int newSize) { p = new Phone(newSize); p.size = 4; } public static final void main(String... params) { final Phone phone = new Phone(3); sendHome(phone,7); System.out.print(phone.size); }}

A. 3

B. 4

C. 7


40. Given the following class, which line of code when inserted below would prevent theclass from compiling?

public class Drink { public static void water() {} public void get() { // INSERT CODE HERE }}

A. water();

B. this.Drink.water();

C. this.water();

D. Drink.water();

41. Given the following method declaration signature, which of the following is a valid callof this method?

public void call(int count, String me, String... data)

A. call(9,"me",10,"Al")

B. call(5)

C. call(2,"home","sweet")

D. call("answering","service")

42. Which statement about a static variable is true?

A. The value of a static variable must be set when the variable is declared or in astatic initialization block.

B. It is not possible to read static final variables outside the class in which they aredefined.

C. It is not possible to reference static methods using static imports.

D. A static variable is always available in all instances of the class.

43. Which of the following is not a true statement?

A. The first line of every constructor is a call to the parent constructor via the super()command.

B. A class does not have to have a constructor explicitly defined.

C. A constructor may pass arguments to the parent constructor.

D. A final instance variable whose value is not set when they are declared or in aninitialization block should be set by the constructor.

44. How many final modifiers would need to be removed for this application to compile?

package park;public class Tree { public final static long numberOfTrees; public final double height; static {} { final int initHeight = 2; height = initHeight; } static { numberOfTrees = 100; height = 4; }}

A. None

B. One

C. Two

D. The code will not compile regardless of the number of final modifiers removed.


package jungle;public class RainForest extends Forest { public RainForest(long treeCount) { this.treeCount = treeCount+1; } public static void main(String[] birds) { System.out.print(new RainForest(5).treeCount); }}class Forest { public long treeCount; public Forest(long treeCount) { this.treeCount = treeCount+2; }}

A. 5

B. 6

C. 8



public class ChooseWisely { public ChooseWisely() { super(); } public int choose(int choice) { return 5; } public int choose(short choice) { return 2; } public int choose(long choice) { return 11; } public static void main(String[] path) { System.out.print(new ChooseWisely().choose((byte)2+1)); }

}

A. 5

B. 2

C. 11



package sports;public class Football { public static Long getScore(Long timeRemaining) { return 2*timeRemaining; // m1 } public static void main(String[] refs) { final int startTime = 4; System.out.print(getScore(startTime)); // m2 }}

A. 8

B. The code does not compile because of line m1.

C. The code does not compile because of line m2.


48. Which of the following is a valid method name in Java?

A. $sprint()

B. \jog13()

C. walk#()

D. %run()

49. Assume there is a class Bouncer with a protected variable. Methods in which class canaccess this variable?

A. Only subclasses of Bouncer

B. Any subclass of Bouncer or any class in the same package as Bouncer

C. Only classes in the same package as Bouncer

D. Any superclass of Bouncer

50. Given the following two classes, each in a different package, which line inserted belowallows the second class to compile?

package commerce;public class Bank { public void withdrawal(int amountInCents) {} public void deposit(int amountInCents) {}

} package employee;// INSERT CODE HEREpublic class Teller { public void processAccount(int depositSlip, int withdrawalSlip) { withdrawal(withdrawalSlip); deposit(depositSlip); }}

A. import static commerce.Bank.*;

B. static import commerce.Bank.*;

C. import static commerce.Bank;


Chapter 7Working with InheritanceTHE OCA EXAM TOPICS COVERED IN THIS PRACTICE TEST INCLUDETHE FOLLOWING:

Working with Inheritance

Describe inheritance and its benefits

Develop code that makes use of polymorphism; develop code that overridesmethods; differentiate between the type of a reference and the type of an object

Determine when casting is necessary

Use super and this to access objects and constructors

Use abstract classes and interfaces


package theater;class Cinema { private String name; public Cinema(String name) {this.name = name;}}public class Movie extends Cinema { public Movie(String movie) {} public static void main(String[] showing) { System.out.print(new Movie("Another Trilogy").name); }}

A. None

B. One

C. Two

D. Three

2. Which modifier can be applied to an abstract interface method?

A. protected

B. static

C. final

D. public


package radio;public class Song { public void playMusic() { System.out.print("Play!"); } private static int playMusic() { System.out.print("Music!"); } public static void main(String[] tracks) { new Song().playMusic(); }}

A. Play!

B. Music!


D. The code compiles but the answer cannot be determined until runtime.

4. Which of the following statements about inheritance is true?

A. Inheritance allows objects to access commonly used attributes and methods.

B. Inheritance always leads to simpler code.

C. All primitives and objects inherit a set of methods.

D. Inheritance allows you to write methods that reference themselves.

5. Given the class declaration below, which value cannot be inserted into the blank linethat would allow the code to compile?

package mammal;interface Pet {}public class Canine implements Pet { public ___________ getDoggy() { return this; }}

A. Class

B. Pet

C. Canine

D. Object

6. Imagine you are working with another team to build an application. You aredeveloping code that uses a class that the other team has not finished writing yet.Which element of Java would best facilitate this development, allowing easyintegration once the other team’s code is complete?

A. An abstract class

B. An interface

C. static methods

D. An access modifier


package vehicles;class Automobile { private final String drive() { return "Driving vehicle"; }}class Car extends Automobile { protected String drive() { return "Driving car"; }}public class ElectricCar extends Car { public final String drive() { return "Driving electric car"; } public static void main(String[] wheels) { final Car car = new ElectricCar(); System.out.print(car.drive()); }}

A. Driving vehicle

B. Driving electric car

C. Driving car


8. Which of the following statements about inheritance is correct?

A. Java does not support multiple inheritance.

B. Java allows multiple inheritance using abstract classes.

C. Java allows multiple inheritance using non-abstract classes.

D. Java allows multiple inheritance using interfaces.

9. How many changes need to be made to the classes below to properly override thewatch() method?

package entertainment;class Television { protected final void watch() {}}public class LCD extends Television { Object watch() {}}

A. One

B. Two

C. Three

D. None; the code compiles as is.

10. Which of the following statements about overriding a method is incorrect?

A. The return types must be covariant.

B. The access modifier of the method in the child class must be the same or broaderthan the method in the superclass.

C. A checked exception thrown by the method in the parent class must be thrown bythe method in the child class.

D. A checked exception thrown by a method in the child class must be the same ornarrower than the exception thrown by the method in the parent class.


package machines;class Computer { protected final int process() { return 5; }}public class Laptop extends Computer { public final int process() { return 3; } public static void main(String[] chips) { System.out.print(new Laptop().process());

}}

A. 5

B. 3



12. Given that FileNotFoundException is a subclass of IOException, what is the output ofthe following application?

package edu;import java.io.*;class School { public int getNumberOfStudentsPerClassroom(String... students) throws IOException { return 3; } public int getNumberOfStudentsPerClassroom() throws IOException { return 9; }}public class HighSchool extends School { public int getNumberOfStudentsPerClassroom() throws FileNotFoundException { return 2; } public static void main(String[] students) throws IOException { School school = new HighSchool(); System.out.print(school.getNumberOfStudentsPerClassroom()); }}

A. 2

B. 3

C. 9


13. Which modifier can be applied to an interface method?

A. protected

B. static

C. private

D. final


package track;interface Run {

default void walk() { System.out.print("Walking and running!"); }}interface Jog { default void walk() { System.out.print("Walking and jogging!"); }} public class Sprint implements Run, Jog { public void walk() { System.out.print("Sprinting!"); } public static void main() { new Sprint().walk(); }}

A. Walking and running!

B. Walking and jogging!

C. Sprinting!


15. Which of the following statements about interfaces is not true?

A. An interface can extend another interface.

B. An interface can implement another interface.

C. A class can implement two interfaces.

D. A class can extend another class.


package transport; class Ship { protected int weight = 3; private int height = 5; public int getWeight() { return weight; } public int getHeight() { return height; }} public class Rocket extends Ship { public int weight = 2; public int height = 4; public void printDetails() { System.out.print(super.getWeight()+","+super.height); } public static final void main(String[] fuel) { new Rocket().printDetails(); }}

A. 2,5

B. 3,4

C. 3,5


17. Fill in the blanks: Excluding default and static methods, a(n) ____________cancontain both abstract and concrete methods, while a(n) ____________containsonly abstract methods.

A. concrete class, abstract class

B. concrete class, interface

C. interface, abstract class

D. abstract class, interface

18. Which statement about the following class is correct?

package shapes; abstract class Triangle { abstract String getDescription();}class RightTriangle extends Triangle { protected String getDescription() { return "rt"; } // g1}public abstract class IsoscelesRightTriangle extends RightTriangle { // g2 public String getDescription() { return "irt"; } public static void main(String[] edges) { final Triangle shape = new IsoscelesRightTriangle(); // g3 System.out.print(shape.getDescription()); }}

A. The code does not compile due to line g1.

B. The code does not compile due to line g2.

C. The code does not compile due to line g3.

D. The code compiles and runs without issue.

19. Given that Short and Integer extend Number, what type can be used to fill in the blankin the class below to allow it to compile?

package band; interface Horn { public Integer play(); }abstract class Woodwind { public Short play() {return 3;} }public final class Saxophone extends Woodwind implements Horn { public ___________play() { return null; }}

A. Integer

B. Short

C. Number


20. Fill in the blanks: A class ____________an interface, while a class____________an abstract class.

A. extends, implements

B. extends, extends

C. implements, extends

D. implements, implements


package paper; abstract class Book { protected static String material = "papyrus"; public Book() {} public Book(String material) {this.material = material;}}public class Encyclopedia extends Book { public static String material = "cellulose"; public Encyclopedia() {super();} public String getMaterial() {return super.material;} public static void main(String[] pages) { System.out.print(new Encyclopedia().getMaterial()); }}

A. papyrus

B. cellulose



22. The following diagram shows two reference variables pointing to the same Bunnyobject in memory. The reference variable myBunny is of type Bunny, while unknownBunnyis of an unknown data type. Which statement about the reference variables is nottrue? For this question, assume the instance methods and variables shown in thediagram are marked public.

A. If the unknownBunny reference does not have access to the same variables andmethods that myBunny has access to, it can be explicitly cast to a reference type thatdoes.

B. The data type of unknownBunny must be Bunny or a subclass of Bunny.

C. If the data type of unknownBunny is Bunny, it has access to all of the same methodsand variables as myBunny.

D. The data type of unknownBunny could be an interface, class, or abstract class.

23. Which of the following modifiers can be applied to an abstract method?

A. final

B. private

C. default

D. protected


package space; interface Sphere { default String getName() { return "Unknown"; }}abstract class Planet { abstract String getName();}public class Mars extends Sphere implements Planet { public Mars() { super(); } public String getName() { return "Mars"; } public static void main(final String[] probe) { System.out.print(((Planet)new Mars()).getName()); }}

A. Mars

B. Unknown

C. The code does not compile due to the declaration of Sphere.

D. The code does not compile for another reason.

25. Which of the following statements is correct?

A. A reference to a class can be assigned to a subclass reference without an explicitcast.

B. A reference to a class can be assigned to a superclass reference without an explicitcast.

C. A reference to an interface can be assigned to a reference of a class thatimplements the interface without an explicit cast.

D. A reference to a class that implements an interface can be assigned to an interfacereference only with an explicit cast.

26. Of the following four modifiers, choose the one that is not implicitly applied to allinterface variables.

A. final

B. abstract

C. static

D. public


package race;abstract class Car { static { System.out.print("1"); } public Car(String name) { super(); System.out.print("2"); } { System.out.print("3"); }}public class BlueCar extends Car { { System.out.print("4"); } public BlueCar() { super("blue"); System.out.print("5"); } public static void main(String[] gears) { new BlueCar(); }}

A. 23451

B. 12354

C. 13245


28. Fill in the blank: Overloaded and overridden methods always have____________ .

A. the same parameter list

B. different return types

C. the same method name

D. covariant return types


package sports;abstract class Ball { protected final int size; public Ball(int size) { this.size = size; }}interface Equipment {}public class SoccerBall extends Ball implements Equipment { public SoccerBall() { super(5); } public Ball get() { return this; } public static void main(String[] passes) { Equipment equipment = (Equipment)(Ball)new SoccerBall().get(); System.out.print(((SoccerBall)equipment).size); }}

A. 5

B. The code does not compile due an invalid cast.

C. The code does not compile for a different reason.

D. The code compiles but throws a ClassCastException at runtime.

30. Fill in the blanks: A class that defines an instance variable with the same name as avariable in the parent class is referred to as ____________a variable, while a classthat defines a static method with the same signature as a static method in a parentclass is referred to as ____________a method.

A. hiding, overriding

B. overriding, hiding

C. hiding, hiding

D. replacing, overriding


package shapes; abstract class Parallelogram { private int getEqualSides() {return 0;}

}abstract class Rectangle extends Parallelogram { public static int getEqualSides() {return 2;} // x1}public final class Square extends Rectangle { public int getEqualSides() {return 4;} // x2 public static void main(String[] corners) { final Square myFigure = new Square(); // x3 System.out.print(myFigure.getEqualSides()); }}

A. The code does not compile due to line x1.

B. The code does not compile due to line x2.

C. The code does not compile due to line x3.



package flying; class Rotorcraft { protected final int height = 5; abstract int fly();}public class Helicopter extends Rotorcraft { private int height = 10; protected int fly() { return super.height; } public static void main(String[] unused) { Helicopter h = (Helicopter)new Rotorcraft(); System.out.print(h.fly()); }}

A. 5

B. 10


D. The code compiles but produces a ClassCastException at runtime.

33. Fill in the blanks: A class may be assigned to a(n) _____________ referencevariable automatically but requires an explicit cast when assigned to a(n)_____________ reference variable.

A. subclass, outer class

B. superclass, subclass

C. subclass, superclass

D. abstract class, concrete class

34. Fill in the blank: A(n) ____________is the first non-abstract subclass that isrequired to implement all of the inherited abstract methods.

A. abstract class

B. abstraction

C. concrete class

D. interface

35. How many compiler errors does the following code contain?

package animal;interface CanFly { public void fly() {}}final class Bird { public int fly(int speed) {}}public class Eagle extends Bird implements CanFly { public void fly() {}}

A. None

B. One

C. Two

D. Three

36. Which of the following is not an attribute common to both abstract classes andinterfaces?

A. They both can contain static variables.

B. They both can contain default methods.

C. They both can contain static methods.

D. They both can contain abstract methods.


package musical;interface SpeakDialogue { default int talk() { return 7; } }interface SingMonologue { default int talk() { return 5; } }public class Performance implements SpeakDialogue, SingMonologue { public int talk(String... x) { return x.length; } public static void main(String[] notes) { System.out.print(new Performance().talk(notes)); }}

A. 7

B. 5


D. The code compiles without issue, but the output cannot be determined untilruntime.

38. Which of the following is a virtual method?

A. protected instance methods

B. static methods

C. private instance methods

D. final instance methods

39. Fill in the blanks: An interface ____________another interface, while a class____________another class.

A. implements, extends

B. extends, extends

C. implements, implements

D. extends, implements


class Math { public final double secret = 2;}class ComplexMath extends Math { public final double secret = 4;}public class InfiniteMath extends ComplexMath { public final double secret = 8; public static void main(String[] numbers) { Math math = new InfiniteMath(); System.out.print(math.secret); }}

A. 2

B. 4

C. 8


41. Given the following method and the fact that FileNotFoundException is a subclass ofIOException, which of the following method signatures is a valid override by asubclass?

protected void dance() throws FileNotFoundException {}

A. void dance() throws IOException

B. public void dance() throws IOException

C. private void dance() throws FileNotFoundException

D. public final void dance()

42. Given the class definitions below, which value, when inserted into the blank line, doesnot allow the class to compile?

public class Canine {}public class Dog extends Canine {}public class Wolf extends Canine {}public final class Husky extends Dog {}public class Zoologist { Canine animal; public final void setAnimal(Dog animal) { this.animal = animal; } public static void main(String[] furryFriends) { new Zoologist().setAnimal(_____________); }}

A. new Husky()

B. new Dog()

C. new Wolf()

D. null

43. Which of the following modifiers cannot be applied to an interface method?

A. final

B. default

C. static

D. abstract

44. Which statement about the following application is true?

package party; abstract class House { protected abstract Object getSpace();}abstract class Room extends House { abstract Object getSpace(Object list);}abstract public class Ballroom extends House { protected abstract Object getSpace(); public static void main(String[] squareFootage) { System.out.print("Let's start the party!"); }}

A. It compiles and at runtime prints Let's start the party!

B. It does not compile for one reason.

C. It does not compile for two reasons.

D. It does not compile for three reasons.

45. Fill in the blanks: ____________methods must have a different list of parameters,while ____________methods must have the exact same return type.

A. Overloaded, overridden

B. Inherited, overridden

C. Overridden, overloaded


46. Which of the following statements about no-argument constructors is correct?

A. If a parent class does not include a no-argument constructor, a child class cannotdeclare one.

B. If a parent class does not include a no-argument constructor (nor a default oneinserted by the compiler), a child class must contain at least one constructordefinition.

C. If a parent class contains a no-argument constructor, a child class must contain ano-argument constructor.

D. If a parent class contains a no-argument constructor, a child class must contain atleast one constructor.

47. Fill in the blanks: The ____________determines which attributes exist in memory,while the ____________determines which attributes are accessible by the caller.

A. reference type, signature

B. object type, superclass

C. reference type, object type

D. object type, reference type

48. Given that Integer and Long are subclasses of Number, what type can be used to fill inthe blank in the class below to allow it to compile?

package orchestra;interface MusicCreator { public Number play(); }abstract class StringInstrument { public Long play() {return 3L;} }public class Violin extends StringInstrument implements MusicCreator { public _____________ play() { return 12; }}

A. Long

B. Integer

C. Long or Integer

D. Long or Number

49. Which of the following is the best reason for creating a default interface method?

A. Allow interface methods to be inherited.

B. Add backward compatibility to existing interfaces.

C. Give an interface the ability to create concrete methods.

D. Allow an interface to define a method at the class level.

50. Given that EOFException is a subclass of IOException, what is the output of thefollowing application?

package ai;import java.io.*;class Machine { public boolean turnOn() throws EOFException {return true;}}public class Robot extends Machine { public boolean turnOn() throws IOException {return false;} public static void main(String[] doesNotCompute) throws Exception { Machine m = new Robot(); System.out.print(m.turnOn()); }}

A. true

B. false


D. The code compiles but produces an exception at runtime.

Chapter 8Handling ExceptionsTHE OCA EXAM TOPICS COVERED IN THIS PRACTICE TEST INCLUDETHE FOLLOWING:

Handling Exceptions

Differentiate among checked exceptions, unchecked exceptions, and Errors

Create a try-catch block and determine how exceptions alter normal program flow

Describe the advantages of Exception handling

Create and invoke a method that throws an exception

Recognize common exception classes (such as NullPointerException,ArithmeticException, ArrayIndexOutOfBoundsException, ClassCastException)


package mind;public class Remember { public static void think() throws Exception { // k1 try { throw new Exception(); } } public static void main(String... ideas) throws Exception { think(); }}

A. The code compiles and runs without printing anything.

B. The code compiles but a stack trace is printed at runtime.

C. The code does not compile because of line k1.


2. Choose the answer that lists the keywords in the order that they would be usedtogether.

A. catch, try, finally

B. try, catch, finally

C. finally, catch, try

D. try, finally, catch

3. Which of the following diagrams of java.lang classes shows the inheritance modelproperly?

A.

B.

C.

D.

4. Which of the following Throwable types is it recommended not to catch in a Javaapplication?

A. Error

B. CheckedException

C. Exception

D. RuntimeException


package game;public class Baseball { public static void main(String... teams) { try { int score = 1; System.out.print(score++); } catch (Throwable t) { System.out.print(score++); } finally { System.out.print(score++); } System.out.print(score++); }}

A. 123

B. 124

C. 12


6. Which of the following is a checked exception?

A. ClassCastException

B. IOException

C. ArrayIndexOutOfBoundsException

D. IllegalArgumentException

7. Fill in the blanks: The ____________keyword is used in method declarations, whilethe ____________keyword is used to throw an exception to the surroundingprocess.

A. throws, throw

B. catch, throw

C. throw, throws

D. throws, catch

8. If a try statement has catch blocks for both Exception and IOException, then which ofthe following statements is correct?

A. The catch block for Exception must appear before the catch block for IOException.

B. The catch block for IOException must appear before the catch block for Exception.

C. The catch blocks for these two exception types can be declared in any order.

D. A try statement cannot be declared with these two catch block types because theyare incompatible.


package game;public class Football { public static void main(String officials[]) { try { System.out.print('A'); throw new RuntimeException("Out of bounds!"); } catch (ArrayIndexOutOfBoundsException aioobe) { System.out.print('B'); throw t; } finally { System.out.print('C'); } }}

A. ABC

B. ABC, followed by a stack trace for a RuntimeException

C. AC, followed by a stack trace for a RuntimeException


10. What is the result of compiling and running the following application?

package castles;public class Fortress { public void openDrawbridge() throws Exception { // p1 try { throw new Exception("Circle"); } catch (Exception e) { System.out.print("Opening!"); } finally { System.out.print("Walls"); // p2 } } public static void main(String[] moat) { new Fortress().openDrawbridge(); // p3 }}

A. The code does not compile because of line p1.

B. The code does not compile because of line p2.

C. The code does not compile because of line p3.

D. The code compiles, but a stack trace is printed at runtime.

11. Which of the following exception types must be handled or declared by the method inwhich they are thrown?

A. NullPointerException

B. Exception

C. RuntimeException

D. ArithmeticException


package game;public class BasketBall { public static void main(String[] dribble) { try { System.out.print(1); throw new ClassCastException(); } catch (ArrayIndexOutOfBoundsException ex) { System.out.print(2); } catch (Throwable ex) { System.out.print(3); } finally { System.out.print(4); } System.out.print(5); }}

A. 1345

B. 1235



13. Which of the following statements about a finally block is true?

A. Every line of the finally block is guaranteed to be executed.

B. The finally block is executed only if the related catch block is also executed.

C. The finally statement requires brackets {}.

D. The finally block cannot throw an exception.


package office;import java.io.*;public class Printer { public void print() { try { throw new FileNotFoundException(); } catch (IOException exception) { System.out.print("Z"); } catch (FileNotFoundException enfe) { System.out.print("X"); } finally { System.out.print("Y"); } }

public static void main(String... ink) { new Printer().print(); }}

A. XY

B. ZY


D. The code compiles but a stack trace is printed at runtime.

15. Which keywords are required with a try statement?

I. catch

II. finalize

III. finally

A. I only

B. II only

C. I or III, or both

D. None of these statements are required with a try statement.

16. Which statement about the role of exceptions in Java is incorrect?

A. Exceptions are often used when things “go wrong” or deviate from the expectedpath.

B. An application that throws an exception will terminate.

C. Some exceptions can be avoided programmatically.

D. An application that can properly handle its exception may recover from unexpectedproblems.


package harbor;class CapsizedException extends Exception {}class Transport { public int travel() throws CapsizedException { return 2; };}public class Boat { public int travel() throws Exception { return 4; }; // j1 public static void main(String... distance) throws Exception{ try { System.out.print(new Boat().travel()); } catch (Exception e) ( System.out.print(8); ) }}

A. 4

B. 8

C. The code does not compile due to line j1.


18. Which of following method signatures would not be allowed in a class implementingthe Printer interface?

class PrintException extends Exception {}class PaperPrintException extends PrintException {} public interface Printer { abstract int printData() throws PrintException;}

A. public int printData() throws PaperPrintException

B. public int printData() throws Exception

C. public int printData()


19. Which import statement is required to be declared in order to use the Exception,RuntimeException, and Throwable classes in an application?

A. import java.exception.*;

B. import java.util.exception.*;

C. import java.lang.*;


20. Which statement about the following classes is correct?

class GasException extends Exception {}class Element { public int getSymbol() throws GasException { return -1; } // g1}public class Oxygen extends Element { public int getSymbol() { return 8; } // g2 public void printData() { try { System.out.print(getSymbol()); } catch { // g3 System.out.print("Unable to read data"); } }}

A. The code does not compile because of line g1.

B. The code does not compile because of line g2.

C. The code does not compile because of line g3.


21. Fill in the blanks: A program must handle or declare ____________but shouldnever handle ____________.

A. java.lang.Error, unchecked exceptions

B. checked exceptions, java.lang.Error

C. java.lang.Throwable, java.lang.Error

D. unchecked exceptions, java.lang.Exception


package castles;class CastleUnderSiegeException extends Exception {}class KnightAttackingException extends CastleUnderSiegeException {}public class Citadel { public void openDrawbridge() throws RuntimeException { // q1 try { throw new KnightAttackingException(); } catch (Exception e) { throw new ClassCastException(); } finally { throw new CastleUnderSiegeException(); // q2 } } public static void main(String[] moat) { new Citadel().openDrawbridge(); // q3 }}

A. The code does not compile because of line q1.

B. The code does not compile because of line q2.

C. The code does not compile because of line q3.


23. If an exception matches two or more catch blocks, which catch block is executed?

A. The first one that matches is executed.

B. The last one that matches is executed.

C. All matched blocks are executed.

D. It is not possible to write code like this.


package system;public class Computer { public void compute() throws Exception { throw new RuntimeException("Error processing request");

} public static void main(String[] bits) { try { new Computer().compute(); System.out.print("Ping"); } catch (NullPointerException e) { System.out.print("Pong"); throw e; } }}

A. Ping

B. Pong



25. In the following application, the value of list has been omitted. Assuming the codecompiles without issue, which one of the following is not a possible output ofexecuting this class?

package checkboard; public class Attendance { private Boolean[] list = // value omitted public int printTodaysCount() { int count=0; for(int i=0; i<10; i++) { if(list[i]) ++count; } return count; } public static void main(String[] roster) { new Attendance().printTodaysCount(); }}

A. A stack trace for NullPointerException is printed.

B. A stack trace for ArrayIndexOutOfBoundsException is printed.

C. A stack trace for ClassCastException is printed.


26. Fill in the blanks: A ____________occurs when a program recurses too deeply intoan infinite loop, while a(n) ____________occurs when a reference to a nonexistentobject is acted upon.

A. NoClassDefFoundError, StackOverflowError

B. StackOverflowError, NullPointerException

C. ClassCastException, IllegalArgumentException

D. StackOverflowError, IllegalArgumentException

27. Which of the following is not a reason to add checked exceptions to a methodsignature?

A. To force a caller to handle or declare its exceptions

B. To notify the caller of potential types of problems

C. To ensure that exceptions never cause the application to terminate

D. To give the caller a chance to recover from a problem


package peculiar;public class Stranger { public static String getFullName(String firstName, String lastName) { try { return firstName.toString() + " " + lastName.toString(); } finally { System.out.print("Finished!"); } catch (NullPointerException npe) { System.out.print("Problem?"); } return null; } public static void main(String[] things) { System.out.print(getFullName("Joyce","Hopper")); }}

A. Joyce Hopper

B. Finished!Joyce Hopper

C. Problem?Finished!null


29. Fill in the blanks: A try statement has ____________finally block(s) and____________catch blocks.

A. zero or one, zero or more

B. one, one or more

C. zero or one, zero or one

D. one or more, zero or one


package pond;abstract class Duck { protected int count; public abstract int getDuckies();}

public class Ducklings extends Duck { private int age; public Ducklings(int age) { this.age = age; } public int getDuckies() { return this.age/count; } public static void main(String[] pondInfo) { Duck itQuacks = new Ducklings(5); System.out.print(itQuacks.getDuckies()); }}

A. 0

B. 5



31. Given a try statement, if both the catch block and the finally block each throw anexception, what does the caller see?

A. The exception from the catch block

B. The exception from the finally block

C. Both the exception from the catch block and the exception from the finally block



package zoo;class BigCat { void roar(int level) throw RuntimeException { // m1 if(level<3) throw new IllegalArgumentException("Incomplete"); System.out.print("Roar!"); }}public class Lion extends BigCat { public void roar() { // m2 System.out.print("Roar!!!"); } public static void main(String[] cubs) { final BigCat kitty = new Lion(); // m3 kitty.roar(2); }}

A. The code does not compile because of line m1.




33. Given the following code snippet, which specific exception will be thrown?

final Object exception = new Exception();final Exception data = (RuntimeException)exception;System.out.print(data);

A. ClassCastException

B. RuntimeException

C. NullPointerException


34. Which of the following classes will handle all types in a catch block?

A. Exception

B. Error

C. Throwable

D. RuntimeException

35. In the following application, the values of street and city have been omitted. Whichone of the following is a possible output of executing this class?

I. 350 5th Ave - New York

II. Posted:350 5th Ave - New York

package registration;public class Address { public String getAddress(String street, String city) { try { return street.toString() + " : " + city.toString(); } finally { System.out.print("Posted:"); } } public static void main(String[] form) { String street = // value omitted String city = // value omitted System.out.print(new Address().getAddress(street,city)); }}

A. I only

B. II only

C. I and II


36. If a try statement has catch blocks for both ClassCastException andRuntimeException, then which of the following statements is correct?

A. The catch block for ClassCastException must appear before the catch block forRuntimeException.

B. The catch block for RuntimeException must appear before the catch block forClassCastException.



37. Which of the following is the best scenario to use an exception?

A. The computer caught fire.


C. A caller passes invalid data to a method.

D. A method finishes sooner than expected.


package body;class Organ { public void operate() throws RuntimeException { throw new RuntimeException("Not supported"); }}public class Heart extends Organ { public void operate() throws Exception { System.out.print("beat"); } public static void main(String... cholesterol) throws Exception { try { new Heart().operate(); } finally { } }}

A. beat

B. Not supported



39. Which statement about the following exception statement is correct?

throw new NullPointerException();

A. The code where this is called must include a try-catch block that handles thisexception.

B. The method where this is called must declare a compatible exception.

C. This exception cannot be handled.

D. This exception can be handled with a try-catch block or ignored altogether by the

surrounding method.


package clothing;public class Coat { public Long zipper() throws Exception { try { String checkZipper = (String)new Object(); } catch (Exception e) { throw RuntimeException("Broken!"); } return null; } public static void main(String... warmth) { try { new Coat().zipper(); System.out.print("Finished!"); } catch (Throwable t) {} }}

A. Finished!

B. Finished!, followed by a stack trace

C. The application does not produce any output at runtime.


41. Given the following application, which type of exception will be printed in the stacktrace at runtime?

package carnival;public class WhackAnException { public static void main(String... hammer) { try { throw new ClassCastException(); } catch (IllegalArgumentException e) { throw new IllegalArgumentException(); } catch (RuntimeException e) { throw new NullPointerException(); } finally { throw new RuntimeException(); } }}

A. IllegalArgumentException

B. NullPointerException

C. RuntimeException


42. Which of these method signatures is allowed in a class implementing the Outfielder

interface?

class OutOfBoundsException extends BadCatchException {}class BadCatchException extends Exception {} public interface Outfielder { public void catchBall() throws OutOfBoundsException;}

A. public int catchBall() throws OutOfBoundsException

B. public int catchBall() throws BadCatchException

C. public int catchBall() throws Exception



package city;public class Street { public static void dancing() throws RuntimeException { try { throw new IllegalArgumentException(); } catch (Error) { System.out.print("Unable!"); } } public static void main(String... count) throws RuntimeException { dancing(); }}

A. Unable!

B. The application does not produce any output.

C. The application compiles but produces a stack trace at runtime.



package castles;class DragonException extends Exception {}public class Lair { public void openDrawbridge() throws Exception { // r1 try { throw new Exception("This Exception"); } catch (RuntimeException e) { throw new DragonException(); // r2 } finally { throw new RuntimeException("Or maybe this one"); } } public static void main(String[] moat) throws Exception { new Lair().openDrawbridge(); // r3 }

}

A. The code does not compile because of line r1.

B. The code does not compile because of line r2.

C. The code does not compile because of line r3.


45. If a try statement has catch blocks for both IllegalArgumentException andClassCastException, then which of the following statements is correct?

A. The catch block for IllegalArgumentException must appear before the catch blockfor ClassCastException.

B. The catch block for ClassCastException must appear before the catch block forIllegalArgumentException.




package broken;class Problem implements RuntimeException {}public class BiggerProblem extends Problem { public static void main(String uhOh[]) { try { throw new BiggerProblem(); } catch (BiggerProblem re) { System.out.print("Problem?"); } catch (Problem e) { System.out.print("Handled"); } finally { System.out.print("Fixed!"); } }}

A. Problem?Fixed!

B. Handled.Fixed!

C. Problem?Handled.Fixed!



package lighting;interface Source { void flipSwitch() throws Exception;}public class LightBulb implements Source {

public void flipSwitch() { try { throws new RuntimeException("Circuit Break!"); } finally { System.out.print("Flipped!"); } } public static void main(String... electricity) throws Throwable { final Source bulb = new LightBulb(); bulb.flipSwitch(); }}

A. A stack trace for a RuntimeException

B. Flipped!, followed by a stack trace for a RuntimeException

C. The code does not compile because flipSwitch() is an invalid method override.


48. Given an application that hosts a website, which of the following would most likelyresult in a java.lang.Error being thrown?

A. Two users try to register an account at the same time.

B. The application temporarily loses connection to the network.

C. A user enters their password incorrectly.

D. The application runs out of memory.


package storage;import java.io.*;public class Backup { public void performBackup() { try { throw new IOException("Disk not found"); } catch (Exception e) { try { throw new FileNotFoundException("File not found"); } catch (FileNotFoundException e) { // z1 System.out.print("Failed"); } } } public static void main(String... files) { new Backup().performBackup(); // z2 }}

A. Failed

B. The application compiles but a stack trace is printed at runtime.

C. The code does not compile because of line z1.

D. The code does not compile because of line z2.


package bed;public class Sleep { public static void snore() { try { String sheep[] = new String[3]; System.out.print(sheep[3]); } catch (RuntimeException e) { System.out.print("Awake!"); } finally { throw new Exception(); // x1 } } public static void main(String... sheep) { // x2 new Sleep().snore(); // x3 }}

A. Awake!, followed by a stack trace

B. The code does not compile because of line x1.

C. The code does not compile because of line x2.

D. The code does not compile because of line x3.

Chapter 9Working with Selected Classes from the Java APITHE OCA EXAM TOPICS COVERED IN THIS PRACTICE TEST INCLUDETHE FOLLOWING:

Working with Selected classes from the Java API

Manipulate data using the StringBuilder class and its methods

Create and manipulate Strings

Create and manipulate calendar data using classes from java.time.LocalDateTime, java.time.LocalDate, java.time.LocalTime, java.time.format.DateTimeFormatter,java.time.Period

Declare and use an ArrayList of a given type

Write a simple Lambda expression that consumes a Lambda Predicate expression

1. What is the best reason for using StringBuilder instead of String?

A. StringBuilder adds support for multiple threads.

B. StringBuilder can use == to compare values.

C. StringBuilder saves memory by reducing the number of objects created.

D. StringBuilder supports different languages and encodings.

2. What is not true about a String?

A. It can be created without coding a call to a constructor.

B. It can be reused via the string pool.

C. It is final.

D. It is mutable.

3. Which of the following creates a StringBuilder with a different value than the otheroptions?

A. new StringBuilder().append("clown")

B. new StringBuilder("clown")

C. new StringBuilder("cl").insert(2, "own")

D. All of them create the same value.


StringBuilder teams = new StringBuilder("333");teams.append(" 806");teams.append(" 1601");System.out.print(teams);

A. 333

B. 333 806 1601

C. The code compiles but outputs something else.


5. How many of the types ArrayList, List, and Object can fill in the blank to producecode that compiles?

List frisbees = new ____________();

A. None

B. One

C. Two

D. Three


List<String> tools = new ArrayList<>();tools.add("hammer");tools.add("nail");tools.add("hex key");System.out.println(tools.get(1));

A. hammer

B. hex key

C. nail



StringBuilder sb = new StringBuilder("radical") .insert(sb.length(), "robots");System.out.println(sb);

A. radicarobots

B. radicalrobots




List<String> museums = new ArrayList<>(1);museums.add("Natural History");museums.add("Science");museums.add("Art");museums.remove(2);System.out.println(museums);

A. [Natural History, Science]

B. [Natural History, Art, Science]




12: StringBuilder b = new StringBuilder("12");13: b = b.append("3");14: b.reverse();15: System.out.println(b.toString());

A. 12

B. 123

C. 321


10. What is the main benefit of a lambda expression?

A. It allows you to convert a primitive to a wrapper class.

B. It allows you to change the bytecode while the application is running.

C. It allows you to inherit from multiple classes.

D. It allows you to write code that has the execution deferred.


5: StringBuilder line = new StringBuilder("-");6: StringBuilder anotherLine = line.append("-");7: System.out.print(line == anotherLine);8: System.out.print(" ");9: System.out.print(line.length());

A. false 1

B. false 2

C. true 1

D. true 2

12. The author of this method forgot to include the data type. Which of the followingreference types can fill in the blank to complete this method?

public static void secret( ____________mystery) { mystery.add("metal"); String str = mystery.get(0); int num = mystery.length();}

A. ArrayList

B. ArrayList<String>

C. StringBuilder


13. Which portion of code can be removed so that this line of code continues to compile?

Predicate<StringBuilder> p = (StringBuilder b) > {return true;};

A. Remove StringBuilder b

B. Remove ->

C. Remove { and ;}

D. Remove { return and ;}


20: List<Character> chars = new ArrayList<>();21: chars.add('a');22: chars.add('b');23: chars.set(1, 'c');24: chars.remove(0);25: System.out.print(chars.size() + " " + chars.contains('b'));

A. 1 false

B. 1 true

C. 2 false

D. 2 true


12: String b = "12";13: b += "3";14: b.reverse();15: System.out.println(b.toString());

A. 12

B. 123

C. 321


16. How many of these lines fail to compile?

Predicate<String> pred1 = s > false;Predicate<String> pred2 = (s) > false;Predicate<String> pred3 = String s > false;Predicate<String> pred4 = (String s) > false;

A. One

B. Two

C. Three

D. Four

17. What does the following do?

public class Shoot { interface Target { boolean needToAim(double angle); } static void prepare(double angle, Target t) { boolean ready = t.needToAim(angle); // k1 System.out.println(ready); } public static void main(String[] args) {

prepare(45, d -> d > 5 || d < -5); // k2 }}

A. It prints true.

B. It prints false.

C. It doesn’t compile due to line k1.

D. It doesn’t compile due to line k2.


String teams = new String("694");teams.concat(" 1155");teams.concat(" 2265");teams.concat(" 2869");System.out.println(teams);

A. 694

B. 694 1155 2265 2869

C. The code compiles but outputs something else.


19. Which of these classes are in the java.util package?

I. ArrayList

II. LocalDate

III. String

A. I only

B. II only

C. I and II

D. I, II, and III

20. Which of the answer choices results in a different value being output than the otherthree choices?

StringBuilder sb = new StringBuilder("radical ");sb = ________________________;System.out.print(sb);

A. new StringBuilder("radical ")

.append("robots")

B. new StringBuilder("radical ")

.delete(1, 100)

.append("obots")

.insert(1, "adical r")

C. new StringBuilder("radical ")

.insert(7, "robots")

D. new StringBuilder("radical ")

.insert(sb.length(), "robots")


String[] array = {"Natural History", "Science"};List<String> museums = Arrays.asList(array);museums.set(0, "Art");System.out.println(museums.contains("Art"));

A. true

B. false



22. Which is a true statement?

A. If s.contains("abc") is true, then s.equals("abc") is also true.

B. If s.contains("abc") is true, then s.startsWith("abc") is also true.

C. If s.startsWith("abc") is true, then s.equals("abc") is also true.

D. If s.startsWith("abc") is true, then s.contains("abc") is also true.


20: List<Character> chars = new ArrayList<>();21: chars.add('a');22: chars.add('b');23: chars.set(1, 'c');24: chars.remove(0);25: System.out.print(chars.length());

A. 0

B. 1

C. 2


24. The author of this method forgot to include the data type. Which of the followingreference types can fill in the blank to complete this method?

public static void secret(_____________ mystery) { mystery = mystery.replace("1", "8");

mystery.startsWith("paper"); String s = mystery.toString();}

A. ArrayList

B. String

C. StringBuilder


25. Which statement is true about the following figure while ensuring the code continuesto compile?

A. <> can be inserted at position P without making any other changes.

B. <> can be inserted at position Q without making any other changes.

C. <> can be inserted at both positions P and Q.


26. Which of the following can fill in the blank to make the code compile?

import java.util.function.*;public class Card { public static void main(String[] s) { Predicate<String> pred =____________ > true; }}

A. (Integer i)

B. (Object o)

C. (String s)



5: String line = new String("-");6: String anotherLine = line.concat("-");7: System.out.print(line == anotherLine);8: System.out.print(" ");9: System.out.print(line.length());

A. false 1

B. false 2

C. true 1

D. true 2


Predicate dash = c -> c.startsWith(" ");System.out.println(dash.test("–"));

A. true

B. false



29. Of the classes LocalDate, LocalDateTime, LocalTime, and LocalTimeStamp, how manyinclude hours, minutes, and seconds?

A. One

B. Two

C. Three

D. Four

30. What is the output of the following class?

1: package rocket;2: public class Countdown {3: public static void main(String[] args) {4: String builder = "54321";5: builder = builder.substring(4);6: System.out.println(builder.charAt(2));7: }8: }

A. 2

B. 3

C. 4


31. Which equivalent code can replace i -> i != 0 in the following line?

Predicate<Integer> ip = i > i != 0;

A. i -> { i != 0 }

B. i -> { i != 0; }

C. i -> { return i != 0 }

D. i -> { return i != 0; }


LocalDate xmas = LocalDate.of(2016, 12, 25);xmas.plusDays(-1);System.out.println(xmas.getDayOfMonth());

A. 24

B. 25

C. 26



1: public class Legos {2: public static void main(String[] args) {3: StringBuilder sb = new StringBuilder();4: sb.append("red");5: sb.deleteCharAt(0);6: sb.delete(1, 2);7: System.out.println(sb);8: }9: }

A. e

B. d

C. ed



Predicate clear = c -> c.equals("clear");System.out.println(clear.test("pink"));

A. true

B. false



35. Which starts counting from one rather than zero?

A. Array indexes

B. The index used by charAt in a String

C. The months in a LocalDateTime

D. The months in a LocalTime

36. Which statement is not true of Predicate?

A. A boolean is returned from the method it declares.

B. It is an interface.

C. The method it declares accepts two parameters.

D. The method it declares is named test.

37. Which of these periods represents a larger amount of time?

Period period1 = Period.ofWeeks(1).ofDays(3);Period period2 = Period.ofDays(10);

A. period1

B. period2

C. They represent the same length of time.

D. None of the above. This code does not compile.


import java.time.*;import java.time.format.*; public class HowLong { public static void main(String[] args) { LocalDate newYears = LocalDate.of(2017, 1, 1); Period period = Period.ofDays(1); DateTimeFormatter format = DateTimeFormatter.ofPattern("MM-dd-yyyy"); System.out.print(format.format(newYears.minus(period))); }}

A. 01-01-2017

B. 12-31-2016



39. Which of the following can fill in the blank so the following code prints true?

String happy = " :) - (: ";String really = happy.trim();String question = ______________________;System.out.println(really.equals(question));

A. happy.substring(0, happy.length() - 1)

B. happy.substring(0, happy.length())

C. happy.substring(1, happy.length() - 1)

D. happy.substring(1, happy.length())

40. Which is not a true statement about the Period class?

A. A Period is immutable.

B. A Period is typically used for adding or subtracting time from dates.

C. You can create a Period representing 2 minutes.

D. You can create a Period representing 5 years.

41. What is the output of the following class?

1: package rocket;2: public class Countdown {3: public static void main(String[] args) {4: StringBuilder builder = new StringBuilder("54321");5: builder.substring(2);6: System.out.println(builder.charAt(1));7: }8: }

A. 1

B. 2

C. 3

D. 4


List<Integer> pennies = new ArrayList<>();pennies.add(3);pennies.add(2);pennies.add(1);pennies.remove(2);System.out.println(pennies);

A. [3, 1]

B. [3, 2]



43. The author of this method forgot to include the data type. Which of the followingreference types can best fill in the blank to complete this method?

public static void secret(_____________ mystery) { char ch = mystery.charAt(3); mystery = mystery.insert(1, "more"); int num = mystery.length();}

A. ArrayList

B. String

C. StringBuilder


44. What is the smallest unit you can add to a LocalTime object?

A. Second

B. Millisecond

C. Nanosecond

D. Picosecond


import java.time.*;import java.time.format.*; public class HowLong { public static void main(String[] args) { LocalDate newYears = LocalDate.of(2017, 1, 1); Period period = Period.ofDays(1); DateTimeFormatter format = DateTimeFormatter.ofPattern("mm-dd-yyyy"); System.out.print(format.format(newYears.minus(period))); }}

A. 01-01-2017

B. 12-31-2016



46. Which of the following types can you pass as a parameter to the replace() method onthe String class?

I. char

II. String

III. StringBuilder

A. I

B. I and II

C. II and III

D. I, II, and III

47. How many lines does this code output?

import java.util.*;import java.util.function.*; public class PrintNegative { public static void main(String[] args) { List<String> list = new ArrayList<>();

list.add("-5"); list.add("0"); list.add("5"); print(list, e -> e < 0); } public static void print(List<String> list, Predicate<Integer> p) { for (String num : list) if (p.test(num)) System.out.println(num); }}

A. One

B. Two

C. None. The code does not compile.

D. None. The code throws an exception at runtime.


12: List<String> magazines = new ArrayList();13: magazines.add("Readers Digest");14: magazines.add("People");15: magazines.clear();16: magazines.add("The Economist");17: magazines.remove(1);18: System.out.println(magazines.size());

A. 0

B. 1




public class Costume { public static void main(String[] black) { String witch = 'b'; String tail = "lack"; witch = witch.concat(tail); System.out.println(witch); }}

A. b

B. black




LocalDate xmas = LocalDate.of(2016, 12, 25);xmas.setYear(2017);System.out.println(xmas.getYear());

A. 2016

B. 2017



Chapter 10OCA Practice ExamThis chapter contains 80 questions and is designed to simulate a real OCA exam. Whileprevious chapters were focused on a specific set of objectives, this chapter covers all ofthe objectives on the exam. We recommend you take this exam only after you score wellon the questions in the individual chapters.

For this chapter, you should try to simulate the real exam experience as much as possible.This means setting aside 150 minutes of uninterrupted time to complete the test, as wellas not looking at any reference material while taking the exam. If you don’t know ananswer to a question, complete it as best you can and move on to the next question, justas you would on a real exam.

Remember, the exam permits writing material, such as a whiteboard. If you do not have awhiteboard handy, you can just use blank sheets of paper and a pencil. If you do well onthis test, then you are hopefully ready to take the real exam. With that said, good luck!

1. What is the output if this class is run with java Indexing cars carts?

public class Indexing { public static void main(String... books) { StringBuilder sb = new StringBuilder(); for (String book : books) sb.insert(sb.indexOf("c"), book); System.out.println(sb); }}

A. cars

B. cars carts

C. ccars arts


E. The code compiles but throws an exception at runtime.

2. Fill in the blanks: The operators +=,__________ ,__________ ,__________,__________ , and ++ are listed in increasing or the same level of operatorprecedence. (Choose two.)

A. –, +, =, --

B. %, *, /, +

C. =, +, /, *

D. ^, *, -, ==

E. *, /, %, --

3. Which of the following are valid JavaBean signatures? (Choose three.)

A. public byte getNose(String nose)

B. public void setHead(int head)

C. public String getShoulders()

D. public long isMouth()

E. public void gimmeEars()

F. public boolean isToes()

4. Which of the following are true? (Choose two.)

20: int[] crossword [] = new int[10][20];21: for (int i = 0; i < crossword.length; i++)22: for (int j = 0; j < crossword.length; j++)23: crossword[i][j] = 'x'; 24: System.out.println(crossword.size());

A. One line needs to be changed for this code to compile.

B. Two lines need to be changed for this code to compile.

C. Three lines need to be changed for this code to compile.

D. If the code is fixed to compile, none of the cells in the 2D array have a value of 0.

E. If the code is fixed to compile, half of the cells in the 2D array have a value of 0.

F. If the code is fixed to compile, all of the cells in the 2D array have a value of 0.

5. Which of the following statements about java.lang.Error are most accurate? (Choosetwo.)

A. An Error should be thrown if a file system resource becomes temporarilyunavailable.

B. An application should never catch an Error.

C. Error is a subclass of Exception, making it a checked exception.

D. It is possible to catch and handle an Error thrown in an application.

E. An Error should be thrown if a user enters invalid input.

6. Given a class that uses the following import statements, which class would beautomatically accessible without using its full package name? (Choose three.)

import forest.Bird;import jungle.tree.*;import savana.*;

A. forest.Bird

B. savana.sand.Wave

C. jungle.tree.Huicungo

D. java.lang.Object

E. forest.Sloth

F. forest.ape.bonobo

7. How many of the following variables represent immutable objects?

ArrayList l = new ArrayList();String s = new String();StringBuilder sb = new StringBuilder();LocalDateTime t = LocalDateTime.now();

A. None

B. One

C. Two

D. Three

E. Four

F. None of the above—this code doesn’t compile.


StringBuilder builder = new StringBuilder("Leaves growing");do { builder.delete(0, 5);} while (builder.length() > 5);System.out.println(builder);

A. Leaves growing

B. ing

C. wing




package reality;public class Equivalency { public static void main(String[] edges) { final String ceiling = "up"; String floor = new String("up"); final String wall = new String(floor); System.out.print((ceiling==wall) +" "+(floor==wall) +" "+ceiling.equals(wall)); }}

A. false false false

B. true true true

C. false true true

D. false false true

E. It does not compile.

10. How many times does the following code print true?

1: public class Giggles {2: public static void main(String[] args) {3: String lol = "lol";4: System.out.println(lol.toUpperCase() == lol);5: System.out.println(lol.toUpperCase() == lol.toUpperCase());6: System.out.println(lol.toUpperCase().equals(lol));7: System.out.println(lol.toUpperCase().equals(lol.toUpperCase()));8: System.out.println(lol.toUpperCase().equalsIgnoreCase(lol));9: System.out.println(lol.toUpperCase()10: .equalsIgnoreCase(lol.toUpperCase()));11: } }

A. One

B. Two

C. Three

D. Four

E. Five

F. None. The code does not compile.

11. Which lines can be removed together without stopping the code from compiling andwhile printing the same output? (Choose three.)

14: String race = "";15: outer:16: do {17: inner:18: do {19: race += "x";20: } while (race.length() <= 4);21: } while (race.length() < 4);22: System.out.println(race);

A. Lines 15 and 17

B. Lines 15, 16, and 21

C. Line 17

D. Lines 17, 18, and 20

E. Line 20

F. Line 21

12. Which of the following do not compile when filling in the blank? (Choose two.)

long bigNum = ____________;

A. 1234

B. 1234.0

C. 1234.0L

D. 1234l

E. 1234L

F. 1_234

13. How many lines does this program print?

import java.time.*;public class OnePlusOne {

public static void main(String... nums) { LocalTime time = LocalTime.of(1, 11); while (time.getHour() < 1) { time.plusHours(1); System.out.println("in loop"); } }}

A. None

B. One

C. Two


E. The code does not compile.


1: package fun;2: public class Sudoku {3: static int[][] game;4:5: public static void main(String args[]) {6: game[3][3] = 6;7: Object[] obj = game;8: obj[3] = 'X';9: System.out.println(game[3][3]);10: }11: }

A. 6

B. X


D. The code compiles but throws a NullPointerException at runtime.

E. The code compiles but throws a different exception at runtime.

F. The output is not guaranteed.

15. Which of the following use generics and compile without warnings? (Choose two.)

A. List<String> a = new ArrayList();

B. List<> b = new ArrayList();

C. List<String> c = new ArrayList<>();

D. List<> d = new ArrayList<>();

E. List<String> e = new ArrayList<String>();

F. List<> f = new ArrayList<String>();

16. Which of the following are true right before the main() method ends? (Choose two.)

public static void main(String[] args) { String shoe1 = new String("sandal"); String shoe2 = new String("flip flop"); String shoe3 = new String("croc"); shoe1 = shoe2; shoe2 = shoe3; shoe3 = shoe1;}

A. No objects are eligible for garbage collection.

B. One object is eligible for garbage collection.

C. Two objects are eligible for garbage collection.

D. No objects are guaranteed to be garbage collected.

E. One object is guaranteed to be garbage collected.

F. Two objects are guaranteed to be garbage collected.

17. How many lines of the following application do not compile?

package ocean;class BubbleException extends Exception {}class Fish { Fish getFish() throws BubbleException { throw new RuntimeException("fish!"); }}public final class Clownfish extends Fish { public final Clownfish getFish() { throw new RuntimeException("clown!"); } public static void main(String[] bubbles) { final Fish f = new Clownfish(); f.getFish(); System.out.println("swim!"); }}

A. None. The code compiles and prints swim!.

B. None. The code compiles and prints a stack trace.

C. One

D. Two

E. Three


import java.util.*;import java.util.function.*;

public class PrintNegative { public static void main(String[] args) { List<Integer> list= new ArrayList<>(); list.add(-5); list.add(0); list.add(5); print(list, e -> e < 0); } public static void print(List<Integer> list, Predicate<Integer> p) { for (Integer num : list) if (p.test(num)) System.out.println(num); }}

A. One

B. Two

C. Three

D. None. It doesn’t compile.

E. None. It throws an exception at runtime.

19. Which keywords are required with a try statement?

I. finalize

II. catch

III. throws

IV. finally

A. I only

B. II only

C. III only

D. IV only

E. I or II, or both

F. None of the above


12: int result = 8;13: loop: while (result > 7) {14: result++;15: do {16: result--;17: } while (result > 5);18: break loop;

19: }20: System.out.println(result);

A. 5

B. 7

C. 8




package reptile;public class Alligator { static int teeth; double scaleToughness; public Alligator() { teeth++; } public void snap(int teeth) { System.out.print(teeth+" "); teeth--; } public static void main(String[] unused) { new Alligator().snap(teeth); new Alligator().snap(teeth); }}

A. 0 1

B. 1 1

C. 1 2

D. 2 2


F. The code compiles but produces an exception at runtime.


public class Costume { public static void main(String[] black) { String witch = "b"; String tail = "lack"; witch.concat(tail); System.out.println(witch); }}

A. b

B. black

C. lack



23. Which modifiers can be independently applied to an interface method? (Choosethree.)

A. default

B. protected

C. static

D. private

E. final

F. abstract


public class Shoelaces { public static void main(String[] args) { String tie = null; while (tie = null) tie = "shoelace"; System.out.print(tie); }}

A. null

B. shoelace

C. shoelaceshoelace


E. This is an infinite loop.

F. The code compiles but throws an exception at runtime.

25. What statements are true about compiling a Java class file? (Choose two.)

A. If the file does not contain a package statement, then the compiler considers theclass part of the java.lang package.

B. The compiler assumes every class implicitly imports the java.lang.* package.

C. The compiler assumes every class implicitly imports the java.util.* package.

D. Java requires every file to declare a package statement.

E. Java requires every file to declare at least one import statement.

F. If the class declaration does not extend another class, then it implicitly extends thejava.lang.Object class.


package woods;interface Plant { default String grow() { return "Grow!"; }}interface Living { public default String grow() { return "Growing!"; }}public class Tree implements Plant, Living { // m1 public String grow(int height) { return "Super Growing!"; } public static void main(String[] leaves) { Plant p = new Tree(); // m2 System.out.print(((Living)p).grow()); // m3 }}

A. Grow!

B. Growing!

C. Super Growing!

D. It does not compile because of line m1.

E. It does not compile because of line m2.

F. It does not compile because of line m3.


public static void main(String... args) { String name = "Desiree"; int _number = 694; boolean profit$$$; System.out.println(name + " won. " + _number + " profit? " + profit$$$);}

A. The declaration of name does not compile.

B. The declaration of _number does not compile.

C. The declaration of profit$$$ does not compile.

D. The println statement does not compile.

E. The code compiles and runs successfully.

F. The code compiles and throws an exception at runtime.

28. Fill in the blanks: Given a variable x, __________ decreases the value of x by 1 andreturns the original value, while __________ increases the value of x by 1 andreturns the new value.

A. x--, ++x

B. x--, x++

C. --x, x++

D. --x, ++x

29. Given the following two classes in the same package, which constructors containcompiler errors? (Choose three.)

public class Big { public Big(boolean stillIn) { super(); }} public class Trouble extends Big { public Trouble() {} public Trouble(int deep) { super(false); this(); } public Trouble(String now, int... deep) { this(3); } public Trouble(long deep) { this("check",deep); } public Trouble(double test) { super(test>5 ? true : false); }}

A. public Big(boolean stillIn)

B. public Trouble()

C. public Trouble(int deep)

D. public Trouble(String now, int... deep)

E. public Trouble(long deep)

F. public Trouble(double test)

30. Which of the following can replace the comment so this code outputs 100? (Choosetwo.)

public class Stats { // INSERT CODE public static void main(String[] math) { System.out.println(max - min); }}

A. final int min, max = 100;

B. final int min = 0, max = 100;

C. int min, max = 100;

D. int min = 0, max = 100;

E. static int min, max = 100;

F. static int min = 0, max = 100;

31. Which of the following statements are true about Java operators and statements?(Choose two.)

A. Both right-hand sides of the ternary expression will be evaluated at runtime.

B. A switch statement may contain at most one default statement.

C. A single if-then statement can have multiple else statements.

D. The | and || operator are interchangeable, always producing the same results atruntime.

E. The ! operator may not be applied to numeric expressions.


1: public class Legos {2: public static void main(String[] args) {3: StringBuilder sb = new StringBuilder();4: sb.append("red");5: sb.deleteCharAt(0);6: sb.delete(1, 1);7: System.out.println(sb);8: }9: }

A. r

B. e

C. ed

D. red



33. Which of the following is a valid method name in Java? (Choose two.)

A. _____()

B. %run()

C. check-Activity()

D. $Hum2()

E. sing\\3()

F. po#ut ()

34. Which of the following statements about inheritance are true? (Choose two.)

A. Inheritance is better than using static methods for accessing data in other classes.

B. Inheritance allows a method to be overridden in a subclass, possibly changing theexpected behavior of other methods in a superclass.

C. Inheritance allows objects to inherit commonly used attributes and methods.

D. It is possible to create a Java class that does not inherit from any other.

E. Inheritance tends to make applications more complicated.

35. Which of the following statements about Java are true?

I. The java command uses . to separate packages.

II. Java supports functional programming.

III. Java is object oriented.

IV. Java supports polymorphism.

A. I only

B. II only

C. II and III

D. I, III, and IV

E. I, II, III, and IV

F. None are true.


String[][] listing = new String[][] { { "Book", "34.99" }, { "Game", "29.99" }, { "Pen", ".99" } };System.out.println(listing.length + " " + listing[0].length);

A. 2 2

B. 2 3

C. 3 2

D. 3 3



37. Which of the following variable types is permitted in a switch statement? (Choosethree.)

A. Character

B. Byte

C. Double

D. long

E. String

F. Object

38. What does the following do?

public class Shoot { interface Target { boolean needToAim(double angle); } static void prepare(double angle, Target t) { boolean ready = t.needToAim(angle); // k1 System.out.println(ready); } public static void main(String[] args) { prepare(45, d => d > 5 || d < -5); // k2 }}

A. It prints true.

B. It prints false.

C. It doesn’t compile due to line k1.

D. It doesn’t compile due to line k2.

E. It doesn’t compile due to another line.

39. Which of the following is a valid code comment in Java? (Choose three.)

A. /** Insert */ in next method **/

B. /****** Find the kitty cat */

C. // Is this a bug?

D. / Begin method - performStart() /

E. /*** TODO: Call grandma ***/

F. # Updated code by Patti

40. Given the following two classes, each in a different package, which lines allow thesecond class to compile when inserted independently? (Choose two.)

package food;public class Grass { public static int seeds = 10; public static Grass getGrass() {return new Grass();}} package woods;// INSERT CODE HEREpublic class Deer { public void eat() { getGrass();

System.out.print(seeds); }}

A. import static food.Grass.getGrass;

import static food.Grass.seeds;

B. import static food.*;

C. static import food.Grass.*;

D. import food.Grass.*;

E. static import food.Grass.getGrass;

static import food.Grass.seeds;

F. import static food.Grass.*;


import java.util.*;public class Museums { public static void main(String[] args) { String[] array = {"Natural History", "Science", "Art"}; List<String> museums = Arrays.asList(array); museums.remove(2); System.out.println(museums); }}

A. [Natural History, Science]

B. [Natural History, Science, Art]



42. Which of the following substitutions will compile? (Choose two.)

public class Underscores { public String name = "Sherrin"; public void massage() { int zip = 10017; }}

A. Change name to _name

B. Change 10017 to _10017

C. Change 10017 to 10017_

D. Change 10017 to 10_0_17

E. Change int to _int

43. What is the result of the following when called as java counting.Binary?

package counting;import java.util.*;public class Binary { public static void main(String[] args) { args = new String[] {"0", "1", "01", "10" }; Arrays.sort(args); System.out.println(Arrays.toString(args)); }}

A. []

B. [0, 01, 1, 10]

C. [0, 01, 10, 1]

D. [0, 1, 01, 10]



44. Fill in the blanks: Using the _____________ and _____________ modifierstogether allows a variable to be accessed from any class, without requiring an instancevariable.

A. final, package-private

B. class, static

C. protected, instance

D. public, static

E. default, public


import java.util.*;public class Exams { public static void main(String[] args) { List<String> exams = Arrays.asList("OCA", "OCP"); for (String e1 : exams) for (String e2 : exams) System.out.print(e1 + " " + e2); System.out.println(); }}

A. One

B. Four

C. Five



46. Which of the following are true statements? (Choose two.)

A. The javac command compiles a source text file into a set of machine instructions.

B. The java command compiles a .class file into a .java file.

C. The javac command compiles a .java file into a .class file.

D. The javac command compiles a source text file into a bytecode file.

E. The java command compiles a .java file into a .class file.

F. The javac command compiles a .class file into a .java file.

47. How many of the following lines of code compile?

char one = Integer.parseInt("1");Character two = Integer.parseInt("2");int three = Integer.parseInt("3");Integer four = Integer.parseInt("4");short five = Integer.parseInt("5");Short six = Integer.parseInt("6");

A. None

B. One

C. Two

D. Three

E. Four

F. Five

48. Given the application below, what data types can be inserted into the blank that wouldallow the code to print 3? (Choose three.)

public class Highway { public int drive(long car) { return 2; } public int drive(double car) { return 3; } public int drive(int car) { return 5; } public int drive(short car) { return 3; } public static void main(String[] gears) { ____________ value = 5; System.out.print(new Highway().drive(value)); }}

A. boolean

B. short

C. int

D. byte

E. long

F. float

49. How many times does this code print true?

import java.time.*;public class Equality { public void main(String[] args) { System.out.println(new StringBuilder("zelda") == new StringBuilder("zelda")); System.out.println(3 == 3); System.out.println("bart" == "bart"); System.out.println(new int[0] == new int[0]); System.out.println(LocalTime.now() == LocalTime.now()); }}

A. None

B. One

C. Two

D. Three



package ballroom;public class Dance { public static void swing(int... beats) throws ClassCastException { try { System.out.print("1"+beats[2]); // p1 } catch (RuntimeException e) { System.out.print("2"); } catch (Exception e) { System.out.print("3"); } finally { System.out.print("4"); } } public static void main(String... music) { new Dance().swing(0,0); // p2 System.out.print("5"); }}

A. 145

B. 1045

C. 24, followed by a stack trace

D. 245

E. The code does not compile because of line p1.

F. The code does not compile because of line p2.


List<String> drinks = Arrays.asList("can", "cup");for (int container = drinks.size(); container > 0; container++) { System.out.print(drinks.get(container-1) + ",");}

A. can,cup,

B. cup,can,




52. Which of the following method signatures are valid declarations of an entry point in aJava application? (Choose three.)

A. public static void main(String... widgets)

B. public static void main(String sprockets)

C. protected static void main(String[] args)

D. public static int void main(String[] arg)

E. public static final void main(String []a)

F. public static void main(String[] data)

53. Given the application below and the choices available, which lines must all beremoved to allow the code to compile? (Choose three.)

1: package year;2: public class Seasons {3: public static void main(String[] time) {4: final long winter = 10;5: final byte season = 2;6: int fall = 4;7: final short summer = 3;8: switch(season) {9: case 1:10: case winter: System.out.print("winter");11: default:12: case fall: System.out.print("fall");13: case summer: System.out.print("summer");14: default:15: }16: }17: }

A. Line 8

B. Line 9

C. Line 10

D. Line 11

E. Line 12

F. Line 13

54. Given the application below, which lines do not compile? (Choose three.)

package furryfriends;interface Friend { protected String getName(); // h1}class Cat implements Friend { String getName() { // h2 return "Kitty"; }}public class Dog implements Friend { String getName() throws RuntimeException { // h3 return "Doggy"; } public static void main(String[] adoption) { Friend friend = new Dog(); // h4 System.out.print(((Cat)friend).getName()); // h5 System.out.print(((Dog)null).getName()); // h6 }}

A. Line h1

B. Line h2

C. Line h3

D. Line h4

E. Line h5

F. Line h6

55. Which of the following are unchecked exceptions? (Choose three.)

A. FileNotFoundException

B. ArithmeticException

C. IOException

D. Exception

E. IllegalArgumentException

F. RuntimeException


package ranch;public class Cowboy { private int space = 5; private double ship = space < 2 ? 1 : 10; // g1 public void printMessage() { if(ship>1) { System.out.println("Goodbye"); } if(ship<10 && space>=2) System.out.println("Hello"); // g2 else System.out.println("See you again"); } public static final void main(String... stars) { new Cowboy().printMessage(); }}

A. It only prints Hello.

B. It only prints Goodbye.

C. It only prints See you again.

D. It does not compile because of line g1.

E. It does not compile because of line g2.


57. Given the following three class declarations, which sets of access modifiers can beinserted, in order, into the blank lines below that would allow all of the classes tocompile? (Choose three.)

package wake;public class Alarm { ____________static int clock; ____________long getTime() {return clock;}} package wake;public class Coffee { private boolean bringCoffee() { return new Alarm().clock<10;}} package sleep;public class Snooze extends wake.Alarm { private boolean checkTime() { return getTime()>10;}}

A. protected and package-private (blank)

B. public and public

C. package-private (blank) and protected

D. protected and protected

E. private and public

F. package-private (blank) and package-private (blank)

58. Given that FileNotFoundException is a subclass of IOException and Long is a subclassof Number, what is the output of the following application?

package materials; import java.io.*; class CarbonStructure { protected long count; public abstract Number getCount() throws IOException; // q1 public CarbonStructure(int count) { this.count = count; }}public class Diamond extends CarbonStructure { public Diamond() { super(15); } public Long getCount() throws FileNotFoundException { // q2 return count; } public static void main(String[] cost) { try { final CarbonStructure ring = new Diamond(); // q3 System.out.print(ring.getCount()); // q4 } catch (IOException e) { e.printStackTrace(); } }}

A. 15

B. It does not compile because of line q1.

C. It does not compile because of line q2.

D. It does not compile because of line q3.

E. It does not compile because of line q4.

F. It compiles but throws an exception at runtime.

59. How many lines contain a compile error?

1: import java.time.*;2: import java.time.format.*;3:4: public class HowLong {5: public void main(String h) {6: LocalDate newYears = new LocalDate(2017, 1, 1);7: Period period = Period.ofYears(1).ofDays(1);8: DateTimeFormat format = DateTimeFormat.ofPattern("MM-dd-yyyy");9: System.out.print(format.format(newYears.minus(period)));10: }11: }

A. None

B. One

C. Two

D. Three

E. Four

F. Five

60. Which of the following statements about try-catch blocks are correct? (Choose two.)

A. A catch block can never appear after a finally block.

B. A try block must be followed by a catch block.

C. A finally block can never appear after a catch block.

D. A try block must be followed by a finally block.

E. A try block can have zero or more catch blocks.

F. A try block can have zero or more finally blocks.

61. What is printed by the following code snippet?

int fish = 1 + 2 * 5>=2 ? 4 : 2;int mammals = 3 < 3 ? 1 : 5>=5 ? 9 : 7;System.out.print(fish+mammals+"");

A. 49

B. 13

C. 18

D. 99

E. It does not compile.

62. Which of the following statements about objects, reference types, and casting arecorrect? (Choose three.)

A. An object can be assigned to an inherited interface reference variable without anexplicit cast.

B. The compiler can prevent all explicit casts that lead to an exception at runtime.

C. Casting an object to a reference variable does not modify the object in memory.

D. An object can be assigned to a subclass reference variable without an explicit cast.

E. An object can be assigned to a superclass reference variable without an explicitcast.

F. An implicit cast of an object to one of its inherited types can sometimes lead to aClassCastException at runtime.

63. What is the output of the following when run as java EchoFirst seed flower plant?

package unix;

import java.util.*; public class EchoFirst { public static void main(String[] args) { int result = Arrays.binarySearch(args, args[0]); System.out.println(result); }}

A. 0

B. 1

C. 2




64. How many objects are eligible for garbage collection at the end of the main() method?

package store;public class Shoes { static String shoe1 = new String("sandal"); static String shoe2 = new String("flip flop"); public static void shopping() { String shoe3 = new String("croc"); shoe2 = shoe1; shoe1 = shoe3; } public static void main(String... args) { shopping(); }}

A. None

B. One

C. Two

D. Three


65. Fill in the blanks: The ____________keyword is used in method declarations, the____________keyword is used to guarantee a statement will execute even if anexception is thrown, and the ____________keyword is used to throw an exceptionto the surrounding process.

A. throw, finally, throws

B. throws, catch, throw

C. catch, finally, throw

D. finally, catch, throw

E. throws, finally, throw

66. Which statements best describe the result of this code? (Choose two.)

package nyc;public class TouristBus { public static void main(String... args) { String[] nycTourLoops = new String[] { "Downtown", "Uptown", "Brooklyn" }; String[] times = new String[] { "Day", "Night" }; for (int i = 0, j = 0; i < nycTourLoops.length; i++, j++) System.out.println(nycTourLoops[i] + " " + times[j]); }}

A. The println causes one line of output.

B. The println causes two lines of output.

C. The println causes three lines of output.

D. The code terminates successfully.

E. The code throws an exception at runtime.

67. Fill in the blanks: Because of____________ , it is possible to ____________amethod, which allows Java to support____________ .

A. abstract methods, override, inheritance

B. concrete methods, overload, inheritance

C. virtual methods, overload, interfaces

D. inheritance, abstract, polymorphism

E. virtual methods, override, polymorphism.


package calendar;public class Seasons { public static void seasons(String... names) { int l = names[1].length(); // s1 System.out.println(names[l]); // s2 } public static void main(String[] args) { seasons("Summer", "Fall", "Winter", "Spring"); }

}

A. Fall

B. Spring


D. The code throws an exception on line s1.

E. The code throws an exception on line s2.

69. How many lines of the following application contain compilation errors?

1: package percussion;2: 3: interface MakesNoise {}4: abstract class Instrument implements MakesNoise {5: public Instrument(int beats) {}6: public void play() {}7: }8: public class Drum extends Instrument {9: public void play(int count) {}10: public void concert() {11: super.play(5);12: }13: public static void main(String[] beats) {14: MakesNoise mn = new Drum();15: mn.concert();16: }17: }

A. None. The code compiles and runs without issue.

B. One

C. Two

D. Three

E. Four


package fly;public class Helicopter { public int adjustPropellers(int length, String[] type) { length++; type[0] = "LONG"; return length; } public static void main(String[] climb) { final Helicopter h = new Helicopter(); int length = 5; String[] type = new String[1]; length = h.adjustPropellers(length, type); System.out.print(length+","+type[0]);

}}

A. 5,LONG

B. 6,LONG

C. 5,null

D. 6,null



71. How many lines of the following application do not compile?

package castles;class OpenDoorException extends Exception {}class CableSnapException extends OpenDoorException {}public class Palace { public void openDrawbridge() throws Exception { try { throw new Exception("Problem"); } catch (OpenDoorException e) { throw new OpenDoorException(); } catch (CableSnapException ex) { try { throw new OpenDoorException(); } catch (Exception ex) { } finally { System.out.println("Almost done"); } } finally { throw new RuntimeException("Unending problem"); } } public static void main(String[] moat) throws IllegalArgumentException { new Palace().openDrawbridge(); }}

A. None. The code compiles and produces a stack trace at runtime.

B. One

C. Two

D. Three

E. Four

F. Five

72. Choose the best answer: ____________and ____________are two propertiesthat go hand in hand to improve class design by structuring a class with relatedattributes and actions while protecting the underlying data from access by otherclasses.

A. Optimization and platform independence

B. Platform independence and encapsulation

C. Platform independence and inheritance

D. Object orientation and encapsulation

E. Inheritance and polymorphism


string bike1 = "speedy";string bike2 = new String("speedy");boolean test1 = bike1 == bike2;boolean test2 = bike1.equals(bike2);System.out.println(test1 + " " + test2);

A. false false

B. false true

C. true false

D. true true



74. What is the output of the following when run as java EchoFirst seed flower plant?

package unix; import java.util.*; public class EchoFirst { public static void main(String[] args) { Arrays.sort(args); int result = Arrays.binarySearch(args, args[0]); System.out.println(result); }}

A. 0

B. 1

C. 2




75. Which are true statements? (Choose three.)

A. Every do-while loop can be rewritten as a for-each loop.

B. Every for-each loop can be rewritten as a do-while loop.

C. Every for-each loop can be rewritten as a traditional for loop.

D. Every for-each loop can be rewritten as a while loop.

E. Every traditional for loop can be rewritten as a for-each loop.

F. Every while loop can be rewritten as a for-each loop.

76. How many lines does this program print?

import java.time.*;public class OnePlusOne { public static void main(String... nums) { LocalDate time = LocalDate.of(1, 11); while (time.getHour() < 1) { time.plusHours(1); System.out.println("in loop"); } }}

A. None

B. One

C. Two



77. How many objects are eligible for garbage collection immediately before the end of themain() method?

public class Tennis { public static void main(String[] game) { String[] balls = new String[1]; int[] scores = new int[1]; balls = null; scores = null; }}

A. None

B. One

C. Two

D. Three

E. Four


14: int count = 0;15: LocalDate date = LocalDate.of(2017, Month.JANUARY, 1);16: while (date.getMonth() != Month.APRIL)17: date = date.minusMonths(1);18: count++;19: System.out.println(count);

A. 0

B. 1

C. 3

D. 9

E. This is an infinite loop.

F. The code does not compile.

79. How many lines of the following class do not compile?

1: package arctic;2: abstract class Bear {3: protected int sing;4: protected abstract int grunt();5: int sing() {6: return sing;7: }8: }9: public class PolarBear extends Bear {10: int grunt() {11: sing() += 10;12: return super.grunt()+1;13: return 10;14: }15: }

A. None, the class compiles without issue.

B. One

C. Two

D. Three

E. Four

F. Five

80. In which places is the default keyword permitted to be used? (Choose two.)

A. Access modifier in a class

B. Execution path in a switch statement

C. Method name

D. Modifier in an abstract interface method

E. Modifier in an interface method with a body

F. Variable name

PART IIOCP

Chapter 11Java Class DesignTHE OCP EXAM TOPICS COVERED IN THIS PRACTICE TEST INCLUDETHE FOLLOWING:

Java Class Design

Implement encapsulation

Implement inheritance including visibility modifiers and composition

Implement polymorphism

Override hashCode, equals, and toString methods from Object class

Create and use singleton classes and immutable classes

Develop code that uses static keyword on initialize blocks, variables, methods, andclasses

1. Which answer choice can replace line 6 so the code continues to produce the sameoutput?

3: List<String> rug = new ArrayList<>();4: rug.add("circle");5: rug.add("square");6: System.out.println(rug);

A. System.out.println(rug.asString);

B. System.out.println(rug.asString());

C. System.out.println(rug.toString);

D. System.out.println(rug.toString());

2. Which best describes this code?

class Stats { private int data; public int getData() { return data; } public void setData(int data) { this.data = data; }}

A. It is a singleton.

B. It is well encapsulated.

C. It is immutable.

D. It is both well encapsulated and immutable.

3. What design pattern or principle ensures that there will be no more than one instanceof a class?

A. Encapsulation

B. Immutability

C. Singleton

D. Static

4. What is the output of this code?

class Laptop extends Computer { public void startup() { System.out.print("laptop-"); }}public class Computer { public void startup() { System.out.print("computer-"); }

public static void main(String[] args) { Computer computer = new Laptop(); Laptop laptop = new Laptop(); computer.startup(); laptop.startup(); }}

A. computer-laptop-

B. laptop-computer-

C. laptop-laptop-


5. Which method can be correctly inserted into this class to meet the contract of theequals() method? You may assume that text is not null.

class Button { private String text; public int hashCode() { return text.hashCode(); }}

A. public boolean equals(Object o) {

if ( o == null ) return true;

if (! (o instanceof Button)) return false;

return text.equals(o.text);

}

B. public boolean equals(Object o) {

if ( o == null ) return true;

Button b = (Button) o;

return text.equals(b.text);

}

C. public boolean equals(Object o) {


return text.equals(o.text);

}

D. public boolean equals(Object o) {


Button b = (Button) o;

return text.equals(b.text);

}

6. Fill in the blanks: ____________means the state of an object cannot be changedwhile ____________means that it can.

A. Immutability, mutability

B. Rigidity, flexibility

C. Static, instance


7. Which is the first line to fail to compile?

class Tool { void use() { } // r1} class Hammer extends Tool { private void use() { } // r2 public void bang() { } // r3}

A. r1

B. r2

C. r3


8. Which of these classes properly implement(s) the singleton pattern?

class ExamAnswers { private static ExamAnswers instance = new ExamAnswers(); private List<String> answers = new ArrayList<>(); public static List<String> getAnswers() { return instance.answers; }}class TestAnswers { private static TestAnswers instance = new TestAnswers(); private List<String> answers = new ArrayList<>(); public static TestAnswers getTestAnswers() { return instance; } public List<String> getAnswers() { return answers; }}

A. ExamAnswers

B. TestAnswers

C. Both classes

D. Neither class

9. What does the following print?

public class Transport { static interface Vehicle {} static class Bus implements Vehicle {} public static void main(String[] args) { Bus bus = new Bus(); boolean n = null instanceof Bus; boolean v = bus instanceof Vehicle; boolean b = bus instanceof Bus; System.out.println(n + " " + v + " " + b); }}

A. true true true

B. false true true

C. false false false


10. What technique allows multiple variables from the same class to be shared across allinstances of a class?

A. Encapsulation

B. Immutability

C. Singleton

D. Static

11. Which is not a requirement for a class to be immutable?

A. A private constructor is provided.

B. Any instance variables are private.

C. Methods cannot be overridden.

D. There are no setter methods.

12. Which statement is true about encapsulation while providing the broadest accessallowed?

A. Variables are public and methods are private.

B. Variables are public and methods are public.

C. Variables are private and methods are public.

D. Variables are private and methods are private.


class Laptop extends Computer { String type = "laptop";}public class Computer { String type = "computer"; public static void main(String[] args) { Computer computer = new Laptop(); Laptop laptop = new Laptop(); System.out.print(computer.type + "," + laptop.type); }}

A. computer,laptop

B. laptop,computer

C. laptop,laptop


14. Which of these classes is/are immutable?

public final class Flower { private final String name; private final List<Integer> counts; public Flower(String name, List<Integer> counts) { this.name = name; this.counts = counts; } public String getName() { return name; } public List<Integer> getCounts() { return counts; }} public final class Plant { private final String name; private final List<Integer> counts; public Plant(String name, List<Integer> counts) { this.name = name; this.counts = new ArrayList<>(counts); } public String getName() { return name; } public List<Integer> getCounts() { return new ArrayList<>(counts); }}

A. Flower

B. Plant

C. Both classes

D. Neither class

15. Which methods compile?

private static int numShovels;private int numRakes; public int getNumShovels() { return numShovels;} public int getNumRakes() { return numRakes;}

A. Just getNumRakes()

B. Just getNumShovels()

C. Both methods

D. Neither method

16. Which methods compile?

private static int numShovels;private int numRakes; public static int getNumShovels() { return numShovels;} public static int getNumRakes() { return numRakes;}

A. Just getNumRakes()

B. Just getNumShovels()

C. Both methods

D. Neither method

17. How many lines of the main method fail to compile?

11: static interface Vehicle {}12: static class Bus implements Vehicle {}13:14: public static void main(String[] args) {15: Bus bus = new Bus();16:

17: System.out.println(null instanceof Bus);18: System.out.println(bus instanceof Vehicle);19: System.out.println(bus instanceof Bus);20: System.out.println(bus instanceof ArrayList);21: System.out.println(bus instanceof Collection);22: }

A. One

B. Two

C. Three

D. Four

18. Which variable declaration is the first line not to compile?

class Building {}class House extends Building{} public void convert() { Building b = new Building(); House h = new House(); Building bh = new House(); Building p = (House) b; House q = (Building) h; Building r = (Building) bh; House s = (House) bh;}

A. p

B. q

C. r

D. s

19. Which statement is true about the code that can fill in the blank?

class Sticker { public int hashCode() { return 1; } public boolean equals(Object o) { return____________ ; }}

A. It must return false.

B. It must return true.

C. It can return either true or false.

D. None of the above.

20. What change is needed to make Secret well encapsulated?

import java.util.*; public class Secret { private int number = new Random().nextInt(10); public boolean guess(int candidate) { return number == candidate; }}

A. Change number to use a public access modifier.

B. Declare a private constructor.

C. Remove the guess method.

D. None. It is already well encapsulated.

21. Which of these classes best implement(s) the singleton pattern?

class ExamAnswers { private static ExamAnswers instance = new ExamAnswers(); private List<String> answers = new ArrayList<>(); private ExamAnswers() {} public ExamAnswers getExamAnswers() { return instance; } public List<String> getAnswers() { return answers; }}class TestAnswers { private static TestAnswers instance = new TestAnswers(); private List<String> answers = new ArrayList<>(); private TestAnswers() {} public static TestAnswers getTestAnswers() { return instance; } public List<String> getAnswers() { return answers; }}

A. ExamAnswers

B. TestAnswers

C. Both classes

D. Neither class


public class Cars { static { System.out.println("static"); } private static void drive() {

System.out.println("fast"); } public static void main(String[] args) { drive(); drive(); }}

A. One

B. Two

C. Three

D. None of the above. The code does not compile.

23. Which is not a true statement given this diagram?

A. Instance methods in the Blanket class can call the Flashlight class’s turnOn().

B. Instance methods in the Flashlight class can call the Flashlight class’sreplaceBulb().

C. Instance methods in the Phone class can call the Blanket class’s wash().

D. Instance methods in the Tent class can call the Tent class’s pitch().

24. Given the diagram in the previous question, how many of the classes can call thedisplay() method?

A. One

B. Two

C. Three

D. Four


1: class SmartWatch extends Watch {2: private String getType() { return "smart watch"; }3: public String getName(String suffix) {4: return getType() + suffix;5: }6: }7: public class Watch {8: private String getType() { return "watch"; }9: public String getName(String suffix) {10: return getType() + suffix;11: }12: public static void main(String[] args) {13: Watch watch = new Watch();14: SmartWatch smartWatch = new SmartWatch();15: System.out.print(watch.getName(","));16: System.out.print(smartWatch.getName(""));17: }18: }

A. smart watch,watch

B. watch,smart watch

C. watch,watch



public class Transport { static interface Vehicle {} static class Bus implements Vehicle {} static class Van extends Bus {} public static void main(String[] args) { Bus bus = new Van(); Van van = new Van(); Van[] vans = new Van[0]; boolean b = bus instanceof Vehicle; boolean v = van instanceof Vehicle; boolean a = vans instanceof Vehicle[]; System.out.println(b + " " + v + " " + a); }}

A. true true true

B. false true true

C. true false false

D. None of the above. The code does not compile

27. Which of the following correctly fills in the blank so this code compiles and printstrue?

public class Button { private String text; public int hashCode() { return text.hashCode(); } public boolean equals(Object o) { if (____________) return false; Button b = (Button) o; return text.equals(b.text); } public static void main(String[] args) { Button b1 = new Button(); Button b2 = new Button(); b1.text = "mickey"; b2.text = "mickey"; System.out.println(b1.equals(b2)); }}

A. (o instanceof Button)

B. (o instanceOf Button)

C. !(o instanceof Button)

D. !(o instanceOf Button)


class Tool { void use() { } // r1} class Hammer extends Tool { private void use(String s) { } // r2 public void bang() { } // r3}

A. r1

B. r2

C. r3


29. What is lazy instantiation?

A. A technique that can be used in an immutable class to wait until the first use tocreate the object

B. A technique that can be used in a singleton to wait until the first use to create theobject

C. A technique that can be used in an immutable class to save memory when creatingthe object

D. A technique that can be used in a singleton to save memory when creating theobject

30. Which variable declaration is the first line not to compile?

30: class Building {}31: class House extends Building{}32:33: public void convert() {34: Building b = new Building();35: House h = new House();36: Building bh = new House();37: House p = (House) b;38: House q = (House) h;39: House r = (House) bh;40: }

A. p

B. q

C. r


31. Which statement about encapsulation is not true?

A. Encapsulation allows putting extra logic in the getter and setter methods.

B. Encapsulation can use immutable instance variables in the implementation.

C. Encapsulation causes two classes to be more tightly tied together.

D. Encapsulation makes it easier to change the instance variables in the future.

32. Which of these classes is/are immutable?

public class Flower { private final String name; private final List<Integer> counts; public Flower(String name, List<Integer> counts) { this.name = name; this.counts = new ArrayList<>(counts); } public final String getName() { return name; } public final List<Integer> getCounts() { return new ArrayList<>(counts); }} public class Plant { private final String name; private final List<Integer> counts; public Plant(String name, List<Integer> counts) { this.name = name; this.counts = new ArrayList<>(counts);

} public String getName() { return name; } public List<Integer> getCounts() { return new ArrayList<>(counts); }}

A. Flower

B. Plant

C. Both classes

D. Neither class


public class Cars { private static void drive() { static { System.out.println("static"); } System.out.println("fast"); } public static void main(String[] args) { drive(); drive(); }}

A. One

B. Two

C. Three


34. How many of the following pairs of values can fill in the blanks to comply with thecontract of the hashCode() and equals() methods?

class Sticker { public int hashCode() { return _____________; } public boolean equals(Object o) { return _____________; }}

I. 1, false

II. 1, true

III. new Random().nextInt(), false

IV. new Random().nextInt(), true

A. None

B. One

C. Two

D. Three

35. How do you change the value of an instance variable in an immutable class?

A. Call the setter method.

B. Remove the final modifier and set the instance variable directly.

C. Use a method other than Option A or B.

D. You can’t.

36. Which technique or pattern requires instance variables to implement?

A. Is-a

B. Object composition

C. Singleton


37. How many lines of output does the following generate?

public class HowMany { static { System.out.println("any"); } { System.out.println("more"); } public static void main(String[] args) { new HowMany(); new HowMany(); }}

A. Two

B. Three

C. Four



class Tool { default void use() { } // r1}

class Hammer extends Tool { public void use() { } // r2 public void bang() { } // r3}

A. r1

B. r2

C. r3


39. Which variable declaration is the first line to throw a ClassCastException at runtime?

class Building {}class House extends Building{} public void convert() { Building b = new Building(); House h = new House(); Building bh = new House(); House p = (House) b; House q = (House) h; House r = (House) bh;}

A. p

B. q

C. r


40. Which of the following values can fill in the blank for the class to be correctlyimplemented?

class Sticker { public int hashCode(Object o) { return_____________ ; } public boolean equals(Object o) { return true; }}

I. -1

II. 5

III. new Random().nextInt()

A. I

B. I and II

C. I, II, and III

D. I and III

Chapter 12Advanced Java Class DesignTHE OCP EXAM TOPICS COVERED IN THIS PRACTICE TEST INCLUDETHE FOLLOWING:

Advanced Java Class

Develop code that uses abstract classes and methods

Develop code that uses the final keyword

Create inner classes including static inner class, local class, nested class, andanonymous inner class

Use enumerated types including methods, and constructors in an enum type

Develop code that declares, implements and/or extends interfaces and use the@Override annotation

Create and use Lambda expressions

1. Which of the following is required for all valid lambda expressions?

A. ()

B. ->

C. {}

D. Parameter data type(s)


package holiday;enum DaysOff { Thanksgiving, PresidentsDay, ValentinesDay}public class Vacation { public static void main(String... unused) { final DaysOff input = DaysOff.Thanksgiving; switch(input) { default: case DaysOff.ValentinesDay: System.out.print("1"); case DaysOff.PresidentsDay: System.out.print("2"); } }}

A. 1

B. 2

C. 12


3. Fill in the blanks: A functional interface must contain or inherit ____________andmay optionally include____________ .

A. at least one abstract method, the @Override annotation

B. exactly one method, static methods

C. exactly one abstract method, the @FunctionalInterface annotation

D. at least one static method, at most one default method

4. Which of the following class types cannot be marked final or abstract?

A. Static nested class

B. Local inner class

C. Anonymous inner class

D. Member inner class

5. Which of the following is a valid lambda expression?

A. r -> {return 1==2}

B. (q) -> true

C. (x,y) -> {int test; return test>0;}

D. a,b -> true

6. Which of the following properties of an enum can be marked abstract?

A. The enum class definition

B. An enum method

C. An enum value



package world;public class Matrix { private int level = 1; class Deep { private int level = 2; class Deeper { private int level = 5; public void printReality() { System.out.print(level); System.out.print(" "+Matrix.Deep.this.level); System.out.print(" "+Deep.this.level); } } } public static void main(String[] bots) { Matrix.Deep.Deeper simulation = new Matrix().new Deep().new Deeper(); simulation.printReality(); }}

A. 1 1 2

B. 5 2 2

C. 5 2 1


8. A local inner class can access which type of local variables?

I. final

II. private

III. effectively final

A. I only

B. I and II

C. III only

D. I and III


package finance; enum Currency { DOLLAR, YEN, EURO}abstract class Provider { protected Currency c = Currency.EURO;}public class Bank extends Provider { protected Currency c = Currency.DOLLAR; public static void main(String[] pennies) { int value = 0; switch(new Bank().c) { case 0: value--; break; case 1: value++; break; } System.out.print(value); }}

A. 0

B. 1



10. What statement best describes the notion of effectively final in Java?

A. A local variable that is marked final

B. A static variable that is marked final

C. A local variable that is not marked final but whose primitive value or objectreference does not change after it is initialized

D. A local variable that is not marked final but whose primitive value or objectreference does not change after a certain point in the method


package race; interface Drive { int SPEED = 5; default int getSpeed() { return SPEED; }}interface Hover { int MAX_SPEED = 5;

default int getSpeed() { return MAX_SPEED; }}public class Car implements Drive, Hover { public static void main(String[] gears) { class RaceCar extends Car { @Override public int getSpeed() { return 10; } }; System.out.print(new RaceCar().getSpeed()); }}

A. 5

B. 10

C. The code does not compile due to the definition of Racecar.

D. The code does not compile for some other reason.

12. Fill in the blanks: It is possible to extend an ____________but not an____________.

A. interface, abstract class

B. abstract class, enum

C. enum, interface

D. abstract class, interface

13. Which of the following results is not a possible output of this program?

package sea;enum Direction { NORTH, SOUTH, EAST, WEST; };public class Ship { public static void main(String[] compass) { System.out.print(Direction.valueOf(compass[0])); }}

A. WEST is printed.

B. south is printed.

C. An ArrayIndexOutOfBoundsException is thrown at runtime.

D. An IllegalArgumentException is thrown at runtime.

14. Which of the following is not an advantage of using enumerated types in Java?

A. Ensure consistency of data across an application.

B. Offer ability to create new enumerated values at runtime.

C. Provide access to fixed constants whose value does not change during the course ofthe application.

D. Support cases where a value can only take one of a limited number of options.

15. Given the following enum declaration, how many lines contain compilation errors?

package rainbow;enum Light {}public enum Color extends Light { RED, BLUE, ORANGE, GREEN protected Color() {}}

A. None, the code compiles as is.

B. One

C. Two

D. Three

16. Which of the following cannot include a static method in its definition?

A. Abstract class

B. Static nested class

C. Interface

D. Local inner class


package ai; interface Pump { void pump(double psi);}interface Bend extends Pump { void bend(double tensileStrength);}public class Robot { public static final void apply(Bend instruction, double input) { // r1 instruction.bend(input); } public static void main(String... future) { final Robot r = new Robot(); r.apply(x -> System.out.print(x+" bent!"), 5); }}

A. 5.0 bent!

B. The code does not compile because Bend is not a functional interface.



18. What is the best reason for applying the @Override annotation to a method?

A. It is required to implement an interface method.

B. It is required to override a method.

C. The method will fail to compile if it is not actually overriding another method.

D. There are no good reasons other than as a form of documentation.


package space; public class Bottle { public static class Ship { private enum Sail { // w1 TALL {protected int getHeight() {return 100;}}, SHORT {protected int getHeight() {return 2;}}; protected abstract int getHeight(); } public Sail getSail() { return Sail.TALL; } } public static void main(String[] stars) { Bottle bottle = new Bottle(); Ship q = bottle.new Ship(); // w2 System.out.print(q.getSail()); }}

A. TALL

B. The code does not compile because of line w1.

C. The code does not compile because of line w2.

D. The code compiles but the application does not produce any output at runtime.

20. Which of the following is not a valid lambda expression?

A. (Integer j, k) -> 5

B. (p,q) -> p+q

C. (Integer x, Integer y) -> x*y

D. (left,right) -> {return "null";}


1: package fruit;2:3: interface Edible { void eat(); }4: public class ApplePicking {5: public static void main(String[] food) {6: Edible apple = new Edible() {7: @Override8: void eat() {9: System.out.print("Yummy!");10: }11: }

12: }13: }

A. The application completes without printing anything.

B. Yummy!

C. One line of this application fails to compile.

D. Two lines of this application fail to compile.


package forest; public class Woods { static class Tree {} public static void main(String[] leaves) { int water = 10+5; final class Oak extends Tree { // p1 public int getWater() { return water; // p2 } } System.out.print(new Oak().getWater()); }}

A. 15

B. The code does not compile because of line p1.

C. The code does not compile because of line p2.


23. Fill in the blanks: ____________allow Java to support multiple inheritance, andanonymous inner classes can ____________of them.

A. Abstract classes, extend at most one

B. Abstract classes, extend any number

C. Interfaces, implement at most one

D. Interfaces, implement any number


package vessel; class Problem extends Exception {}abstract class Danger { protected abstract void isDanger() throws Problem;}public class SeriousDanger extends Danger { protected void isDanger() throws Exception { // m1 throw new RuntimeException();

} public static void main(String[] will) throws Throwable { // m2 new SeriousDanger().isDanger(); // m3 }}

A. The code does not compile because of line m1




25. Which of the following is not a true statement about interfaces and abstract classes?

A. Interfaces can only extend other interfaces, while abstract classes can extend bothabstract and concrete classes.

B. Unlike abstract classes, interfaces can be marked final.

C. Abstract classes offer support for single inheritance, while interfaces offer supportfor multiple inheritance.

D. All methods and variables in interfaces are public, while abstract classes canuse various access modifiers for their methods and variables, including privatein some cases.


package weather; public class Forecast { public enum Snow { BLIZZARD, SQUALL, FLURRY } public static void main(String[] modelData) { System.out.print(Snow.BLIZZARD.ordinal()); System.out.print(" "+Snow.valueOf("flurry".toUpperCase()).name()); }}

A. 0 FLURRY

B. 1 FLURRY



27. Fill in the blank: The primary reason default interface methods were added to Java isto support____________ .

A. polymorphism

B. concrete methods in interfaces

C. multiple inheritance

D. backward compatibility


package zoo; public class Penguin { private int volume = 1; private class Chick { private static int volume = 3; void chick() { System.out.print("Honk("+Penguin.this.volume+")!"); } } public static void main(String... eggs) { Penguin pen = new Penguin(); final Penguin.Chick littleOne = pen.new Chick(); littleOne.chick(); }}

A. Honk(1)!

B. Honk(3)!


D. The code compiles but the output cannot be determined until runtime.

29. Let’s say Dinosaur is a class that contains a public member inner class calledPterodactyl. Given that dino is an instance of Dinosaur, how would you instantiate anew Pterodactyl from within a static method, such as main()?

A. new Pterodactyl();

B. dino.Pterodactyl();

C. Dinosaur.new Pterodactyl();

D. dino.new Pterodactyl();

30. What is the result of compiling the following program?

package desert; interface CanBurrow { public abstract void burrow();}@FunctionalInterface interface HasHardShell extends CanBurrow {} // k1abstract class Tortoise implements HasHardShell { // k2 public abstract int toughness();}public class DesertTortoise extends Tortoise { // k3 public int toughness() { return 11; }}

A. The code does not compile because of line k1.

B. The code does not compile because of line k2.

C. The code does not compile because of line k3.


31. Which statement(s) about the following Twins class are true?

package clone; interface Alex { default void write() {} static void publish() {} void think();}interface Michael { public default void write() {} public static void publish() {} public void think();} public class Twins implements Alex, Michael { @Override public void write() {} @Override public static void publish() {} @Override public void think() { System.out.print("Thinking..."); }}

I. The class fails to compile because of the write() method.

II. The class fails to compile because of the publish() method.

III. The class fails to compile because of the think() method.

A. I only

B. II only

C. I and II

D. II and III

32. Fill in the blanks: A(n) ____________and a(n) ____________can define staticmethods.

A. abstract class, local inner class

B. anonymous inner class, interface

C. member inner class, enum

D. enum, static inner class

33. Which lambda expression can replace the instance of new BiologyMaterial() in theScientist class and produce the same results under various inputted values?

package university;

@FunctionalInterface interface Study { abstract int learn(String subject, int duration);} class BiologyMaterial implements Study { @Override public int learn(String subject, int duration) { if(subject == null) return duration; else return duration+1; }} public class Scientist { public static void main(String[] courses) { final Study s = new BiologyMaterial() {}; System.out.print(s.learn(courses[0], Integer.parseInt(courses[1]))); }}

A. (p,q) -> q==null ? p : p+1

B. (c,d) -> {int d=1; return c!=null ? d+1 : d;}

C. (x,y) -> {return x==null ? y : y+1;}


34. Given the following enum declaration, how many lines contain compilation errors?

package myth; public enum Proposition { TRUE(-10) { @Override String getNickName() { return "RIGHT"; }}, FALSE(-10) { public String getNickName() { return "WRONG"; }}, UNKNOWN(0) { @Override public String getNickName() { return "LOST"; }} private final int value; Proposition(int value) { this.value = value; } public int getValue() { return this.value; } protected abstract String getNickName();}

A. None. The code compiles as is.

B. One

C. Two

D. Three


package math;

interface AddNumbers { int add(int x, int y); static int subtract(int x, int y) { return x-y; } default int multiply(int x, int y) { return x*y; }}public class Calculator { protected void calculate(AddNumbers add, int a, int b) { System.out.print(add.add(a, b)); } public static void main(String[] moreNumbers) { final Calculator ti = new Calculator(); ti.calculate((k,p) -> p+k+1, 2, 5); // j1 }}

A. 8

B. The code does not compile because AddNumbers is not a functional interface.

C. The code does not compile because of line j1.


36. Given the class declaration below, what expression can be used to fill in the blank toreturn the size variable defined in the Bottle class, printing 14 at runtime?

package baby; final public class Bottle { final private int size = 14; final protected class Insert { private final int size = 25; public final int getSize() { return_____________ ; } } final Insert insert = new Insert(); final public static void main(String[] feed) { System.out.print(new Bottle().insert.getSize()); }}

A. Bottle.this.size

B. this.size

C. this.Bottle.size

D. The code does not compile, regardless of what is placed in the blank.


package ocean;abstract interface CanSwim { public void swim();}public class Turtle {

public static void main(String[] seaweed) { int distance = 7; CanSwim seaTurtle = { @Override public void swim() { System.out.print(distance); } }; seaTurtle.swim(); }}

A. The application completes without printing anything.

B. 7

C. One line of this application fails to compile.

D. Two lines of this application fail to compile.


package present; interface Toy { String play(); }public class Gift { public static void main(String[] matrix) { abstract class Robot {} class Transformer extends Robot implements Toy { public String name = "GiantRobot"; public String play() {return "DinosaurRobot";} } Transformer prime = new Transformer () { public String play() {return name;} // y1 }; System.out.print(prime.play()+" "+name); }}

A. GiantRobot GiantRobot

B. GiantRobot DinosaurRobot

C. The code does not compile because of line y1.


39. What is the result of compiling the following program?

package ballroom; class Leader {}class Follower {}abstract public class Dancer { public Leader getPartner() { return new Leader(); } abstract public Leader getPartner(int count); // u1}

abstract class SwingDancer extends Dancer { public Follower getPartner() { // u2 return new Follower(); // u3 }}

A. The code does not compile because of line u1.

B. The code does not compile because of line u2.

C. The code does not compile because of line u3.



package prepare;public class Ready { protected static int first = 2; private final short DEFAULT_VALUE = 10; private static class GetSet { int first = 5; static int second = DEFAULT_VALUE; } private GetSet go = new GetSet(); public static void main(String[] begin) { Ready r = new Ready(); System.out.print(r.go.first); System.out.print(", "+r.go.second); }}

A. 2, 5

B. 5, 10

C. The code does not compile because of the GetSet class body.


Chapter 13Generics and CollectionsTHE OCP EXAM TOPICS COVERED IN THIS PRACTICE TEST INCLUDETHE FOLLOWING:

Generics and Collections

Create and use a generic class

Create and use ArrayList, TreeSet, TreeMap, and ArrayDeque objects

Use java.util.Comparator and java.lang.Comparable interfaces

Collections Streams and Filters

Iterate using forEach methods of Streams and List

Describe Stream interface and Stream pipeline

Filter a collection by using lambda expressions

Use method references with Streams

1. Which of the following can fill in the blank to make the code compile?

public class News<________> {}

I. ?

II. News

III. Object

A. None of them

B. I

C. II and III

D. I, II, and III

2. Which method is available on both List and Stream implementations?

A. filter()

B. forEach()

C. replace()

D. sort()

3. We are running a library. Patrons select books by name. They get at the back of thecheckout line. When they get to the front, they scan the book’s ISBN. The checkoutsystem finds the book based on this number and marks the book as checked out. Ofthese choices, which data structures best represent the line to check out the book andthe book lookup to mark it as checked out, respectively?

A. ArrayDeque, TreeMap

B. ArrayDeque, TreeSet

C. ArrayList, TreeMap

D. ArrayList, TreeSet

4. Which cannot fill in the blank for this code to compile?

Collection<String> c = new ____________<>();c.add("pen");c.remove("pen");System.out.println(c.isEmpty());

A. ArrayDeque

B. TreeMap

C. TreeSet

D. All of these can fill in the blank.

5. Suppose we want to implement a Comparator<String> so that it sorts the longest

strings first. You may assume there are no nulls. Which method could implementsuch a comparator?

A. public int compare(String s1, String s2) {

return s1.length() - s2.length();

}

B. public int compare(String s1, String s2) {

return s2.length() – s1.length();

}

C. public int compare(Object obj1, object obj2) {

String s1 = (String) obj1;


return s1.length() - s2.length();

}

D. public int compare(Object obj1, object obj2) {



return s2.length() – s1.length();

}

6. Suppose we want to store JellyBean objects. Which of the following pairs requireJellyBean to implement the Comparable interface or create a Comparator in order toadd them to the Collection?

A. ArrayList and ArrayDeque

B. HashMap and HashSet

C. HashMap and TreeMap

D. TreeMap and TreeSet

7. What is a common reason for a stream pipeline not to run?

A. The source doesn’t generate any items.

B. There are no intermediate operations.

C. The terminal operation is missing.


8. We want this code to print the titles of each book twice. Why doesn’t it?

LinkedList<String> list = new LinkedList<>();list.add("Grapes of Wrath");list.add("1984"); list.forEach(System.out::println); Iterator it = list.iterator();while (it.hasMore()) System.out.println(it.next());

A. The generic type of Iterator is missing.

B. The hasMore() method should be changed to hasNext().

C. The iteration code needs to be moved before the forEach() since the stream is usedup.

D. None of the above. The code does print each book title twice.


ArrayList<Integer> list = new ArrayList<>();list.add(56);list.add(56);list.add(3); TreeSet<Integer> set = new TreeSet<>(list);System.out.print(set.size());System.out.print(" " );System.out.print(set.iterator().next());

A. 2 3

B. 2 56

C. 3 3

D. 3 56

10. What best describes a reduction?

A. An intermediate operation where it filters the stream it receives

B. An intermediate operation where it mathematically divides each element in thestream

C. A terminal operation where a single value is generated by reading each element inthe prior step in a stream pipeline

D. A terminal operation where one element is returned from the prior step in astream pipeline without reading all the elements


5: ArrayDeque<Integer> d = new ArrayDeque<>();

6: d.offer(18);7: d.offer(5);8: d.push(13);9: System.out.println(d.poll() + " " + d.poll());

A. 13 18

B. 18 5

C. 18 13



class Magazine { private String name; public Magazine(String name) { this.name = name; } public int compareTo(Magazine m) { return name.compareTo(m.name); } public String toString() { return name; }}public class Newstand { public static void main(String[] args) { Set<Magazine> set = new TreeSet<>(); set.add(new Magazine("highlights")); set.add(new Magazine("Newsweek")); set.add(new Magazine("highlights")); System.out.println(set.iterator().next()); }}

A. highlights

B. Newsweek




6: List<String> list = new ArrayList<>();7: list.add("Monday");8: list.add(String::new);9: list.add("Tuesday");10: list.remove(0);11: System.out.println(list.get(0));

A. An empty String

B. Monday




List<String> list = new LinkedList<>();list.add("Archie");list.add("X-Men"); list.stream().forEach(s -> System.out.println(s));list.stream().forEach(s -> System.out.println(s));

A. Two

B. Four



15. Which line in the main() method doesn’t compile or points to a class that doesn’tcompile?

1: interface Comic<C> {2: void draw(C c);3: }4: class ComicClass<C> implements Comic<C> {5: public void draw(C c) {6: System.out.println(c);7: }8: }9: class SnoopyClass implements Comic<Snoopy> {10: public void draw(Snoopy c) {11: System.out.println(c);12: }13: }14: class SnoopyComic implements Comic<Snoopy> {15: public void draw(C c) {16: System.out.println(c);17: }18: }19: public class Snoopy {20: public static void main(String[] args) {21: Comic<Snoopy> c1 = c > System.out.println(c);22: Comic<Snoopy> c2 = new ComicClass<>();23: Comic<Snoopy> c3 = new SnoopyClass();24: Comic<Snoopy> c4 = new SnoopyComic();25: }26: }

A. Line 21

B. Line 22

C. Line 23

D. Line 24


Stream<String> s = Stream.of("Atlanta", "Chicago", "New York");long count = s.filter(c -> c.startsWith("C")).count();System.out.print(count);

A. 1

B. 2



17. Fill in the blank to make this code compile:

public class Truck implements Comparable<Truck> { private int id; public Truck(int id) { this.id = id; } @Override ____________________ { return id - t.id; }}

A. public int compare(Truck t)

B. public int compare(Truck t1, Truck t2)

C. public int compareTo(Truck t)

D. public int compareTo(Truck t1, Truck t2)

18. In a stream pipeline, which can return a value other than a Stream?

A. Source

B. Intermediate operation

C. Terminal operation


19. Rewrite this lambda using a constructor reference:

n -> new ArrayList<>(n)

A. ArrayList::new;

B. ArrayList::new();

C. ArrayList::new(n);

D. ArrayList::new[n];


Comparator<Integer> c = (x, y) > y x;List<Integer> ints = Arrays.asList(3, 1, 4);Collections.sort(ints, c);System.out.println(Collections.binarySearch(ints, 1));

A. 0

B. 1


D. The result is not defined.


List<String> list = new LinkedList<>();list.add("Archie");list.add("X-Men"); Stream<String> s = list.stream();s.forEach(System.out::println);s.forEach(System.out::println);

A. Two

B. Four



22. Which option cannot fill in the blank to print Clean socks?

class Wash<T> { T item; public void clean(T item) { System.out.println("Clean " + item); }}public class LaundryTime { public static void main(String[] args) { ________________________ wash.clean("socks"); }}

A. Wash wash = new Wash();

B. Wash wash = new Wash<String>();

C. Wash<String> wash = new Wash<>();

D. All three can fill in the blank.

23. We want this code to print the titles of each book twice. Why doesn’t it?

LinkedList<String> list = new LinkedList<>();list.add("Grapes of Wrath");list.add("1984");

list.stream().forEach(System.out::println); Iterator it = list.iterator();while (it.hasNext()) System.out.println(it.next());

A. The generic type of Iterator is missing.

B. The hasNext() method should be changed to isNext().

C. The iteration code needs to be moved before the forEach() since the stream is usedup.

D. None of the above. The code does print each book title twice.

24. Rewrite this lambda using a method reference:

() -> Math.random()

A. Math.random

B. Math::random

C. Math::random()


25. Which operation can occur more than once in a stream pipeline?

A. Source

B. Intermediate operation

C. Terminal operation


26. Which type allows inserting a null value?

A. ArrayDeque

B. ArrayList

C. TreeSet

D. All of these allow nulls.

27. Fill in the blank so this code outputs three lines:

List<String> list = new ArrayList<>();list.add("Atlanta");list.add("Chicago");list.add("New York");

list.stream().filter(____________).forEach(System.out::println);

A. String::isEmpty

B. ! String::isEmpty

C. String::! isEmpty



TreeMap<String, Integer> map = new TreeMap<>();map.put("3", 3);map.put("three", 3);map.put("THREE", 3);System.out.println(map.firstKey() + " " + map.lastKey());

A. 3 three

B. 3 THREE

C. three 3

D. THREE 3

29. Which fills in the blank in the method signature to allow this code to compile?

import java.util.*;public class ExtendingGenerics { private static <_____________ , U> U add(T list, U element) { list.add(element); return element; } public static void main(String[] args) { List<String> values = new ArrayList<>(); add(values, "duck"); add(values, "duck"); add(values, "goose"); System.out.println(values); }}

A. ? extends Collection<U>

B. ? implements Collection<U>

C. T extends Collection<U>

D. T implements Collection<U>


List<String> list = new ArrayList<>();list.add("Austin");list.add("Boston");list.add("San Francisco");

list.removeIf(a -> a.length() > 10);System.out.println(list.size());

A. 1

B. 2

C. 3



ArrayDeque<Integer> dice = new ArrayDeque<>();dice.offer(3);dice.offer(2);dice.offer(4);System.out.print(dice.stream().filter(n -> n != 4));

A. 2

B. 3



32. Which of the following cannot fill in the blank to make the code compile?

private void output(____________<?> x) { x.forEach(System.out::println);}

A. ArrayDeque

B. Collection

C. TreeMap



List<String> list = new LinkedList<>();list.add("Archie");list.add("X-Men"); list.stream().forEach(System.out.println);list.stream().forEach(System.out.println);

A. Two

B. Four




class Magazine implements Comparable<Magazine> { private String name; public Magazine(String name) { this.name = name; } @Override public int compareTo(Magazine m) { return name.compareTo(m.name); } @Override public String toString() { return name; }}public class Newstand { public static void main(String[] args) { Set<Magazine> set = new TreeSet<>(); set.add(new Magazine("highlights")); set.add(new Magazine("Newsweek")); set.add(new Magazine("highlights")); System.out.println(set.iterator().next()); }}

A. highlights

B. Newsweek




import java.util.*;class Blankie { String color; String getColor() { return color; }}public class PreSchool { public static void main(String[] args) { Blankie b1 = new Blankie(); Blankie b2 = new Blankie(); b1.color = "pink"; List<Blankie> list = Arrays.asList(b1, b2); list.stream().filter(Blankie::getColor).forEach(System.out::println); }}

A. One

B. Two



36. Which statement about a source in a Stream is true?

A. The source is mandatory in a stream pipeline.

B. The source is only allowed to return primitives.

C. The source must be retrieved by calling the stream() method.

D. The source must return a finite number of elements.


List<String> list = new ArrayList<>();list.add("Austin");list.add("Boston");list.add("San Francisco"); long c = list.stream().filter(a -> a.length() > 10).count();System.out.println(c + " " + list.size());

A. 1 1

B. 1 3

C. 2 3


38. Which options can fill in the blanks to print Cleaned 2 items?

import java.util.*;class Wash<T ____________ Collection> { T item; public void clean(T items) { System.out.println("Cleaned " + items.size() + " items"); }}public class LaundryTime { public static void main(String[] args) { Wash<List> wash = new ____________ wash.clean(Arrays.asList("sock", "tie")); }}

A. extends, Wash<ArrayList>();

B. extends, Wash<List>();

C. super, Wash<ArrayList>();

D. super, Wash<List>();

39. Which of the following declares a Comparator where all objects are treated as equal?

A. Comparator<Character> comp = (c1)-> 0;

B. Comparator<Character> comp = (c1)-> {0};

C. Comparator<Character> comp = (c1, c2)-> 0;

D. Comparator<Character> comp = (c1, c2)-> {0};

40. Why can’t String::charAt be used as a method reference?

A. Method references can only be used on static methods.

B. Method references can pass either the instance or the parameter from the lambda,but not both.

C. The charAt() method takes an int rather than Integer parameter.

D. There is no charAt() method in the String class.

Chapter 14Lambda Built-in Functional InterfacesTHE OCP EXAM TOPICS COVERED IN THIS PRACTICE TEST INCLUDE THEFOLLOWING:

Lambda Built-in Functional Interfaces

Use the built-in interfaces included in the java.util.function package such asPredicate, Consumer, Function, and Supplier

Develop code that uses primitive versions of functional interfaces

Develop code that uses binary versions of functional interfaces

Develop code that uses the UnaryOperator interface

1. Fill in the blanks: The____________ functional interface does not take any inputs,

while the____________ functional interface does not return any data.

A. IntConsumer, LongSupplier

B. IntSupplier, Function

C. Supplier, DoubleConsumer

D. UnaryOperator, Consumer

2. Which functional interface takes a long value as an input argument and has anaccept() method?

A. LongConsumer

B. LongFunction

C. LongPredicate

D. LongSupplier


package beach;import java.util.function.*; class Tourist { public Tourist(double distance) { this.distance = distance; } public double distance;}public class Lifeguard { private void saveLife(Predicate<Tourist> canSave, Tourist tourist) { System.out.print(canSave.test(tourist) ? "Saved" : "Too far"); // y1 } public final static void main(String... sand) { new Lifeguard().saveLife(s -> s.distance<4, new Tourist(2)); // y2 }}

A. Saved

B. Too far


D. The code does not compile because of line y2.

4. Which of the following statements about DoubleSupplier and Supplier<Double> is nottrue?

A. Both are functional interfaces.

B. Lambdas for both can return a double value.

C. Lambdas for both cannot return a null value.

D. One supports a generic type, the other does not.

5. Which functional interface, when filled into the blank, allows the class to compile?

package space;import java.util.function.*; public class Asteroid { public void mine(____________ lambda) { // TODO: Apply functional interface } public static void main(String[] debris) { new Asteroid().mine((s,p) -> s+p); }}

A. BiConsumer<Integer,Double>

B. BiFunction<Integer,Double,Double>

C. BiFunction<Integer,Integer,Double>

D. Function<Integer,Double>

6. Assuming the proper generic types are used, which lambda expression cannot beassigned to a ToDoubleBiFunction functional interface reference?

A. (Integer a, Double b) -> {int c; return b;}

B. (h,i) -> (long)h

C. (String u, Object v) -> u.length()+v.length()

D. (x,y) -> {int z=2; return y/z;}

7. Which of the following is not a functional interface in the java.util.functionpackage?

A. BiPredicate

B. DoubleUnaryOperator

C. ObjectDoubleConsumer

D. ToLongFunction


package zoo;import java.util.function.*; public class TicketTaker { private static int AT_CAPACITY = 100; public int takeTicket(int currentCount, IntUnaryOperator<Integer> counter)

{ return counter.applyAsInt(currentCount); } public static void main(String...theater) { final TicketTaker bob = new TicketTaker(); final int oldCount = 50; final int newCount = bob.takeTicket(oldCount,t -> { if(t>AT_CAPACITY) { throw new RuntimeException("Sorry, max has been reached"); } return t+1; }); System.out.print(newCount); }}

A. 51

B. The code does not compile because of lambda expression.


D. The code compiles but prints an exception at runtime.

9. Which functional interface returns a primitive value?

A. BiPredicate

B. CharSupplier

C. LongFunction

D. UnaryOperator

10. Which functional interface, when entered into the blank below, allows the class tocompile?

package groceries;import java.util.*;import java.util.function.*; public class Market { private static void checkPrices(List<Double> prices, ____________scanner) { prices.forEach(scanner); } public static void main(String[] right) { List<Double> prices = Arrays.asList(1.2, 6.5, 3.0); checkPrices(prices, p -> { String result = p<5 ? "Correct" : "Too high"; System.out.println(result); }); } }

A. Consumer

B. DoubleConsumer

C. Supplier<Double>


11. Which of the following three functional interfaces is not equivalent to the other two?

A. BiFunction<Double,Double,Double>

B. BinaryOperator<Double>

C. DoubleFunction<Double>

D. None of the above. All three are equivalent.

12. Which lambda expression can be passed to the magic() method?

package show;import java.util.function.*; public class Magician { public void magic(BinaryOperator<Long> lambda) { lambda.apply(3L, 7L); }}

A. magic((a) -> a)

B. magic((b,w) -> (long)w.intValue())

C. magic((c,m) -> {long c=4; return c+m;})

D. magic((Integer d, Integer r) -> (Long)r+d)

13. What is the output of the following program?

package ai;import java.util.function.*; public class Android { public void wakeUp(Supplier supplier) { // d1 supplier.get(); } public static void main(String... electricSheep) { Android data = new Android(); data.wakeUp(() -> System.out.print("Program started!")); // d2 }}

A. Program started!

B. The code does not compile because of line d1 only.

C. The code does not compile because of line d2 only.

D. The code does not compile because of both lines d1 and d2.

14. Which statement about all UnaryOperator functional interfaces (generic and primitive)

is correct?

A. The input type must be compatible with the return type.

B. Some of them take multiple arguments.

C. They each take a generic argument.

D. They each return a primitive value.

15. Starting with DoubleConsumer and going downward, fill in the missing values for thetable.

Functional Interface # ParametersDoubleConsumer

IntFunction

LongSupplier

ObjDoubleConsumer

A. 0, 1, 1, 1

B. 0, 2, 1, 2

C. 1, 1, 0, 2

D. 1, 1, 0, 1

16. Starting with DoubleConsumer and going downward, fill in the values for the table. Forthe choices below, assume R is a generic type.

Functional Interface Return TypeDoubleConsumer

IntFunction

LongSupplier

ObjDoubleConsumer

A. double, R, long, R

B. R, int, long, R

C. void, int, R, void

D. void, R, long, void

17. Fill in the blanks: In the Collection interface, the method removeIf() takesa____________ , while the method forEach() takes a____________ .

A. Function, Function

B. Predicate, Consumer

C. Predicate, Function

D. Predicate, UnaryOperator


package nesting;import java.util.function.*; public class Doll { private int layer; public Doll(int layer) { super(); this.layer = layer; } public static void open(UnaryOperator<Doll> task, Doll doll) { while((doll = task.accept(doll)) != null) { System.out.print("X"); } } public static void main(String[] wood) { open(s -> { if(s.layer<=0) return null; else return new Doll(s.layer––); }, new Doll(5)); }}

A. XXXXX

B. The code does not compile because of the lambda expression.


D. The code compiles but produces an infinite loop at runtime.

19. Which functional interface has a get() method?

A. Consumer

B. Function

C. Supplier

D. UnaryOperator

20. The following diagram shows input arguments being applied to three functionalinterfaces of unknown type. Which three functional interfaces, inserted in order fromleft to right, could be used to complete the diagram?

A. DoubleBinaryOperator

ToDoubleBiFunction<Integer,Double>

UnaryOperator<Integer>

B. BinaryOperator<Double>BiFunction<Integer,Integer,Double>

UnaryOperator<Integer>

C. Function<Double,Integer>BiFunction<Integer,Integer,Double>

DoubleToIntFunction

D. BiFunction<Integer,Double,Integer>BinaryOperator<Integer>

IntUnaryOperator

21. Which statement about functional interfaces and lambda expressions is not true?

A. A lambda expression may be compatible with multiple functional interfaces.

B. A lambda expression must be assigned to a functional interface when it is declared.

C. A method can return a lambda expression in the form of a functional interfaceinstance.

D. The compiler uses deferred execution to skip determining whether a lambdaexpression compiles or not.

22. Which expression is compatible with the IntSupplier functional interface?

A. () -> 1<10 ? "3" : 4

B. () -> {return 1/0;}

C. () -> return 4

D. System.out::print


package tps;import java.util.*; class Boss { private String name; public Boss(String name) { this.name = name; } public String getName() {return name.toUpperCase();} public String toString() {return getName();}}public class Initech { public static void main(String[] reports) { final List<Boss> bosses = new ArrayList(8); bosses.add(new Boss("Jenny")); bosses.add(new Boss("Ted"));

bosses.add(new Boss("Grace")); bosses.removeIf(s -> s.equalsIgnoreCase("ted")); System.out.print(bosses); }}

A. [JENNY, GRACE]

B. [tps.Boss@4218224c, tps.Boss@815f19a]

C. The code does not compile because of the lambda expression.

D. The code does not compile for a different reason.

24. Which of the following method references can be passed to a method that takesConsumer<Object> as an argument?

I. ArrayList::new

II. String::new

III. System.out::println

A. I only

B. I, II, and III

C. I and III

D. III only

25. Which of the following is a valid functional interface in the java.util.functionpackage?

A. FloatPredicate

B. ToDoubleBiFunction

C. UnaryIntOperator

D. TriPredicate

26. Which functional interface, when filled into the blank, prevents the class fromcompiling?

package morning;import java.util.function.*; public class Sun { public static void dawn(____________ sunrise) {} public void main(String... rays) { dawn(s -> s+1); }}

A. DoubleUnaryOperator

B. Function<String,String>

C. IntToLongFunction

D. UnaryOperator

27. Which functional interface does not have the correct number of generic arguments?

A. BiFunction<T,U,R>

B. DoubleFunction<T,R>

C. ToDoubleFunction<T>

D. ToIntBiFunction<T,U>

28. Which lambda expression, when filled into the blank, allows the code to compile?

package ballroom;import java.util.function.*; public class Dance { public static Integer rest(BiFunction<Integer,Double,Integer> takeABreak) { return takeABreak.apply(3, 10.2); } public static void main(String[] participants) { rest(____________); }}

A. (int n, double e) -> (int)(n+e)

B. (n,w,e) -> System.out::print

C. (s,w) -> 2*w

D. (s,e) -> s.intValue()+e.intValue()

29. Fill in the blank: ____________is the only functional interface that does notinvolve double, int, or long.

A. BooleanSupplier

B. CharPredicate

C. FloatUnaryOperator

D. ShortConsumer


package savings;import java.util.function.*; public class Bank { private int savingsInCents; private static class ConvertToCents { static DoubleToIntFunction f = p -> p*100; } public static void main(String... currency) {

Bank creditUnion = new Bank(); creditUnion.savingsInCents = 100; double deposit = 1.5; creditUnion.savingsInCents += ConvertToCents.f.applyAsInt(deposit); // j1 System.out.print(creditUnion.savingsInCents); }}

A. 200

B. 250

C. The code does not compile because of line j1.


31. Which functional interface takes a double value and has a test() method?

A. DoubleConsumer

B. DoublePredicate

C. DoubleUnaryOperator

D. ToDoubleFunction

32. Given the following class, how many lines contain compilation errors?

1: package showtimes;2: import java.util.*;3: import java.util.function.*;4: public class FindMovie {5: private Function<String> printer;6: protected FindMovie() {7: printer = s -> {System.out.println(s); return s;}8: }9: void printMovies(List<String> movies) {10: movies.forEach(printer);11: }12: public static void main(String[] screen) {13: List<String> movies = new ArrayList<>();14: movies.add("Stream 3");15: movies.add("Lord of the Recursion");16: movies.add("Silence of the Lambdas");17: new FindMovie().printMovies(movies);18: }19: }


B. One

C. Two

D. Three

33. Which lambda expression cannot be assigned to a DoubleToLongFunction functional

interface?

A. a -> null==null ? 1 : 2L

B. e -> (int)(10.0*e)

C. (double m) -> {long p = (long)m; return p;}

D. (Double s) -> s.longValue()

34. Which of the following is not a functional interface in the java.util.functionpackage?

A. DoublePredicate

B. LongUnaryOperator

C. ShortSupplier

D. ToIntBiFunction

35. Which functional interface, when filled into the blank, allows the class to compile?

package sleep;import java.util.function.*; class Sheep {}public class Dream { int MAX_SHEEP = 10; int sheepCount; public void countSheep( ____________backToSleep) { while(sheepCount<MAX_SHEEP) { // TODO: Apply lambda sheepCount++; } } public static void main(String[] dark) { new Dream().countSheep(System.out::println); }}

A. Consumer<Sheep>

B. Function<Sheep,void>

C. UnaryOperator<Sheep>



package pet;import java.util.*;import java.util.function.*; public class DogSearch { void reduceList(List<String> names, Predicate<String> tester) { names.removeIf(tester);

} public static void main(String[] treats) { int MAX_LENGTH = 2; DogSearch search = new DogSearch(); List<String> names = new ArrayList<>(); names.add("Lassie"); names.add("Benji"); names.add("Brian"); MAX_LENGTH += names.size(); search.reduceList(names, d -> d.length()>MAX_LENGTH); System.out.print(names.size()); }}

A. 2

B. 3

C. The code does not compile because of lambda expression.


37. Which functional interface takes two values and has an apply() method?

A. BiConsumer

B. BiFunction

C. BiPredicate

D. DoubleBinaryOperator

38. Which of the following lambda expressions can be passed to a method that takesIntFunction<Integer> as an argument?

I. (Integer f) -> f

II. (v) -> null

III. s -> s

A. I, II, and III

B. II and III only

C. III only



package lot;import java.util.function.*; public class Warehouse { private int quantity = 40; private final BooleanSupplier stock; { stock = () -> quantity>0;

} public void checkInventory() { if(stock.get()) System.out.print("Plenty!"); else { System.out.print("On Backorder!"); } } public static void main(String... widget) { final Warehouse w13 = new Warehouse(); w13.checkInventory(); }}

A. Plenty!

B. On Backorder!

C. The code does not compile because of the checkInventory() method.


40. Which of the following statements about functional interfaces is true?

A. It is possible to define a functional interface that returns two data types.

B. It is possible to define a primitive functional interface that uses float, char, orshort.

C. It is not possible to define a functional interface that does not take any argumentsnor return any value.

D. None of the primitive functional interfaces include generic arguments.

Chapter 15Java Stream APITHE OCP EXAM TOPICS COVERED IN THIS PRACTICE TEST INCLUDETHE FOLLOWING:

Java Stream API

Develop code to extract data from an object using peek() and map() methodsincluding primitive versions of the map() method

Search for data by using search methods of the Stream classes including findFirst,findAny, anyMatch, allMatch, noneMatch

Develop code that uses the Optional class

Develop code that uses Stream data methods and calculation methods

Sort a collection using Stream API

Save results to a collection using the collect method and group/partition data usingthe Collectors class

Use flatMap() methods in the Stream API

1. Which of the following fills in the blank so that the code outputs one line but uses apoor practice?

import java.util.*; public class Cheater { int count = 0; public void sneak(Collection<String> coll) { coll.stream().________________________; } public static void main(String[] args) { Cheater c = new Cheater(); c.sneak(Arrays.asList("weasel")); }}

A. peek(System.out::println)

B. peek(System.out::println).findFirst()

C. peek(r -> System.out.println(r)).findFirst()

D. peek(r -> {count++; System.out.println(r); }).findFirst()

2. Which can fill in the blank to have the code print true?

Stream<Integer> stream = Stream.iterate(1, i > i+1);boolean b = stream.____________(i -> i > 5);System.out.println(b);

A. anyMatch

B. allMatch

C. noneMatch


3. On a DoubleStream, how many of the methods average(), count(), and sum() return anOptionalDouble?

A. None

B. One

C. Two

D. Three

4. How many of the following can fill in the blank to have the code print 44?

Stream<String> stream = Stream.of("base", "ball");stream._____________(s -> s.length()).forEach(System.out::print);

I. map

II. mapToInt

III. mapToObject

A. None

B. One

C. Two

D. Three


IntStream s = IntStream.empty();System.out.print(s.average().getAsDouble());

A. The code prints 0.

B. The code prints 0.0.



6. Which of these stream pipeline operations takes a Predicate as a parameter andreturns an Optional?

A. anyMatch()

B. filter()

C. findAny()



List<Double> list = new ArrayList<>();list.add(5.4);list.add(1.2);Optional<Double> opt = list.stream().sorted().findFirst();System.out.println(opt.get() + " " + list.get(0));

A. 1.2 1.2

B. 1.2 5.4

C. 5.4 5.4


8. Fill in the blank so this code prints 8.0.

IntStream stream = IntStream.of(6, 10);LongStream longs = stream.mapToLong(i -> i);System.out.println(____________);

A. longs.average().get()

B. longs.average().getAsDouble()

C. longs.getAverage().get()

D. longs.getAverage().getAsDouble()

9. How many of these collectors can fill in the blank to make this code compile?

Stream<Character> chars = Stream.of( 'o', 'b', 's', 't', 'a', 'c', 'l', 'e');chars.map(c -> c).collect(Collectors.____________ );

I. toArrayList()

II. toList()

III. toMap()

A. None

B. One

C. Two

D. Three


import java.util.*; public class MapOfMaps { public static void main(String[] args) { Map<Integer, Integer> map = new HashMap<>(); map.put(9, 3); Map<Integer, Integer> result = map.stream().map((k,v) > (v,k)); System.out.println(result.keySet().iterator().next()); }}

A. 3

B. 9



11. Which of the following creates an Optional that returns true when callingopt.isPresent()?

I. Optional<String> opt = Optional.empty();

II. Optional<String> opt = Optional.of(null);

III. Optional<String> opt = Optional.ofNullable(null);

A. I

B. I and II

C. I and III



Stream<String> s = Stream.of("speak", "bark", "meow", "growl");BinaryOperator<String> merge = (a, b) > a;Map<Integer, String> map = s.collect(toMap(String::length, k > k, merge));System.out.println(map.size() + " " + map.get(4));

A. 2 bark

B. 2 meow

C. 4 bark



1: package reader;2: import java.util.stream.*;3:4: public class Books {5: public static void main(String[] args) {6: IntegerStream pages = IntegerStream.of(200, 300);7: IntegerSummaryStatistics stats = pages.summaryStatistics();8: long total = stats.getSum();9: long count = stats.getCount();10: System.out.println(total + "-" + count);11: }12: }

A. 500-0

B. 500-2



14. If this method is called with Stream.of("hi"), how many lines are printed?

public static void print(Stream<String> stream) { Consumer<String> print = System.out::println; stream.peek(print) .peek(print) .map(s -> s) .peek(print) .forEach(print);}

A. Three

B. Four

C. The code compiles but does not output anything.


15. What is true of the following code?

Stream<Character> stream = Stream.of('c', 'b', 'a'); // z1stream.sorted().findAny().ifPresent(System.out::println); // z2

A. It is guaranteed to print the single character a.

B. It can print any single character of a, b, or c.

C. It does not compile because of line z1.

D. It does not compile because of line z2.

16. Suppose you have a stream pipeline where all the elements are of type String. Whichof the following can be passed to the intermediate operation sorted()?

A. (s,t) -> s.length() - t.length()

B. String::isEmpty

C. Both of these

D. Neither of these

17. Fill in the blanks so that both methods produce the same output for all inputs.

private static void longer(Optional<Boolean> opt) { if (opt.____________()) System.out.println("run: " + opt.get());}private static void shorter(Optional<Boolean> opt) { opt.map(x -> "run: " + x).____________(System.out::println);}

A. isNotNull, isPresent

B. ifPresent, isPresent

C. isPresent, forEach

D. isPresent, ifPresent

18. What is the output of this code?

Stream<Boolean> bools = Stream.iterate(true, b > !b);Map<Boolean, List<Boolean>> map = bools.limit(1) .collect(partitioningBy(b -> b));System.out.println(map);

A. {true=[true]}

B. {false=null, true=[true]}

C. {false=[], true=[true]}



Set<String> set = new HashSet<>();set.add("tire-");List<String> list = new LinkedList<>();Deque<String> queue = new ArrayDeque<>();queue.push("wheel-");Stream.of(set, list, queue) .flatMap(x -> x.stream()) .forEach(System.out::print);

A. [tire-][wheel-]

B. tire-wheel-

C. None of the above.



Stream<String> s = Stream.of("over the river", "through the woods", "to grandmother's house we go");s.filter(n -> n.startsWith("t")) .sorted(Comparator::reverseOrder) .findFirst() .ifPresent(System.out::println);

A. over the river

B. through the woods

C. to grandmother's house we go


21. Which fills in the blank so the code is guaranteed to print 1?

Stream<Integer> stream = Stream.of(1, 2, 3);System.out.println(stream.____________);

A. findAny()

B. first()

C. min()


22. Which of the following can be the type for x?

private static void spot(____________ x) { x.filter(y -> ! y.isEmpty()) .map(y -> 8) .ifPresent(System.out::println);}

I. List<String>

II. Optional<Collection>

III. Optional<String>

IV. Stream<Collection>

A. I

B. IV

C. II and III

D. II and IV

23. Which can fill in the blank to have the code print true?

Stream<Integer> stream = Stream.iterate(1, i > i);boolean b = stream.____________(i -> i > 5);System.out.println(b);

A. anyMatch

B. allMatch

C. noneMatch


24. What collector turns the stream at left to the Map at right?

A. grouping()

B. groupingBy()

C. partitioning()

D. partitioningBy()

25. Which fills in the blank for this code to print 667788?

IntStream ints = IntStream.empty();IntStream moreInts = IntStream.of(66, 77, 88);Stream.of(ints, moreInts).____________(x -> x).forEach(System.out::print);

A. flatMap

B. flatMapToInt

C. map


26. Fill in the blank so this code prints 8.0. Note that it must not printOptionalDouble[8.0].

LongStream stream = LongStream.of(6, 10);LongSummaryStatistics stats = stream.summaryStatistics();System.out.println(____________);

A. stats.avg()

B. stats.average()

C. stats.average().get()

D. stats.getAverage()

27. Which can independently fill in the blank to output No dessert today?

import java.util.*;public class Dessert { public static void main(String[] yum) { eatDessert(Optional.of("Cupcake")); } private static void eatDessert(Optional<String> opt) { System.out.println(opt.____________); }}

A. get("No dessert today")

B. orElse("No dessert today")

C. orElseGet(() -> "No dessert today")



Stream<Character> chars = Stream.generate(() > 'a');chars.filter(c -> c < 'b') .sorted() .findFirst() .ifPresent(System.out::print);

A. a

B. The code runs successfully without any output.

C. The code enters an infinite loop.


29. How many of the following can fill in the blank to have the code print the single digit9?

LongStream stream = LongStream.of(9);stream.____________(p -> p).forEach(System.out::print);

I. mapToDouble

II. mapToInt

III. mapToLong

A. None

B. One

C. Two

D. Three

30. Suppose you have a stream with one element and the codestream.xxxx.forEach(System.out::println). Filling in xxxx from top to bottom in thetable, how many elements can be printed out?

xxxx Number elements printedfilter()

flatMap()

map()

A. Zero or one, zero or more, exactly one

B. Zero or one, exactly one, zero or more

C. Zero or one, zero or more, zero or more

D. Exactly one, zero or more, zero or more


Stream<Character> stream = Stream.of('c', 'b', 'a');System.out.println(stream.sorted().findFirst());

A. It is guaranteed to print the single character a.

B. It can print any single character of a, b, or c.




public class Compete { public static void main(String[] args) { Stream<Integer> is = Stream.of(8, 6, 9); Comparator<Integer> c = (a, b) > a b; is.sort(c).forEach(System.out::print); }}

A. 689

B. 986

C. The code does not compile



class Ballot { private String name; private int judgeNumber; private int score; public Ballot(String name, int judgeNumber, int score) { this.name = name; this.judgeNumber = judgeNumber; this.score = score; } // all getters and setters} public class Speaking { public static void main(String[] args) { Stream<Ballot> ballots = Stream.of( new Ballot("Mario", 1, 10), new Ballot("Christina", 1, 8), new Ballot("Mario", 2, 9), new Ballot("Christina", 2, 8) ); Map<String, Integer> scores = ballots.collect( groupingBy(Ballot::getName, summingInt(Ballot::getScore))); // w1 System.out.println(scores.get("Mario")); }}

A. The code prints 2.

B. The code prints 19.

C. The code does not compile due to line w1.

D. The code does not compile due to a different line.

34. Which can fill in the blank so this code outputs true?

import java.util.function.*;import java.util.stream.*; public class HideAndSeek { public static void main(String[] args) { Stream<Boolean> hide = Stream.of(true, false, true); boolean found = hide.filter(b -> b).__________(); System.out.println(found); }}

A. Only anyMatch

B. Only allMatch

C. Both anyMatch and allMatch

D. The code does not compile with any of these options.


Set<String> set = new HashSet<>();set.add("tire-");List<String> list = new LinkedList<>();Deque<String> queue = new ArrayDeque<>();queue.push("wheel-");Stream.of(set, list, queue) .flatMap(x -> x) .forEach(System.out::print);

A. [tire-][wheel-]

B. tire-wheel-

C. None of the above


36. When working with a Stream<String>, which of these types can be returned from thecollect() terminal operator by passing arguments to Collectors.groupingBy()?

I. Map<Integer, List<String>>

II. Map<Boolean, HashSet<String>>

III. List<String>

A. I

B. II

C. I and II

D. I, II, and III

37. Which line can replace line 18 without changing the output of the program?

1: class Runner {2: private int numberMinutes;3: public Runner(int n) {4: numberMinutes = n;5: }6: public int getNumberMinutes() {7: return numberMinutes;8: }9: public boolean isFourMinuteMile() {10: return numberMinutes < 4*60;11: }12: }13: public class Marathon {14: public static void main(String[] args) {15: Stream<Runner> runners = Stream.of(new Runner(250),

16: new Runner(600), new Runner(201));17: long count = runners18: .filter(Runner::isFourMinuteMile)19: .count();20: System.out.println(count);21: }22: }

A. .map(Runner::isFourMinuteMile)

B. .mapToBool(Runner::isFourMinuteMile).filter(b -> b == true)

C. .mapToBoolean(Runner::isFourMinuteMile) .filter(b -> b == true)


38. Which method is not available on the IntSummaryStatistics class?

A. getCountAsLong()

B. getMax()

C. toString()

D. None of the above—all three methods are available.

39. Which can fill in the blank so this code outputs Caught it?

import java.util.*;public class Catch { public static void main(String[] args) { Optional opt = Optional.empty(); try { apply(opt); } catch (IllegalArgumentException e) { System.out.println("Caught it"); } } private static void apply(Optional<Exception> opt) { opt.__________(IllegalArgumentException::new); }}

A. orElse

B. orElseGet

C. orElseThrow

D. None of the above. The main() method does not compile.

40. A developer tries to rewrite a method that uses flatMap() without using thatintermediate operator. Which pair of method calls shows the withoutFlatMap()method is not equivalent to the withFlatMap() method?

public static void main(String[] args) { List<String> list = new LinkedList<>(); Deque<String> queue = new ArrayDeque<>(); queue.push("all queued up"); queue.push("last");} private static void withFlatMap(Collection<?> coll) { Stream.of(coll) .flatMap(x -> x.stream()) .forEach(System.out::print); System.out.println();} private static void withoutFlatMap(Collection<?> coll) { Stream.of(coll) .filter(x -> !x.isEmpty()) .map(x -> x) .forEach(System.out::print); System.out.println();}

A. withFlatMap(list); withoutFlatMap(list);

B. withFlatMap(queue); withoutFlatMap(queue);

C. Both pairs disprove the claim.

D. Neither pair disproves this claim.

Chapter 16Exceptions and AssertionsTHE OCP EXAM TOPICS COVERED IN THIS PRACTICE TEST INCLUDE THEFOLLOWING:

Exceptions and Assertions

Use try-catch and throw statements

Use catch, multi-catch, and finally clauses

Use Autoclose resources with a try-with-resources statement

Create custom exceptions and Auto-closeable resources

Test invariants by using assertions

1. If a try, a catch, and a finally statement are used together but no exception is

generated, which blocks are executed and in which order?

A. try

B. try, catch

C. try, catch, finally

D. try, finally

2. Fill in the blanks: A try statement__________ a catch or a finally block, while atry-with-resources statement __________.

A. is not required to contain, is not required to contain either

B. is not required to contain, must contain one of them

C. must contain, is not required to contain either

D. must contain, must contain a catch block


package park; class LostBallException extends Exception {}public class Ball { public void toss() throw LostBallException { throw new ArrayStoreException(); } public static void main(String[] bouncy) { try { new Ball().toss(); } catch (Throwable e) { System.out.print("Caught!"); } }}

A. Caught!

B. The code does not compile because LostBallException is not handled or declaredin the main() method.

C. The code does not compile because ArrayStoreException is not handled ordeclared in the toss() method.


4. Which symbol(s) can be used to separate exception types in a multi-catch statement?

I. &

II. |

III. ||

A. II only

B. III only

C. II and III

D. I, II, and III

5. What is the result of executing the following application with assertions enabled?

1: package ice;2: public class Igloo {3: public static void main(String[] bricks) {4: int flakes = 10;5: double assert = 7.0;6: assert (true :"");7: assert flakes++>5;8: }9: }

A. It throws an AssertionError at runtime.

B. It prints nothing at runtime.

C. Exactly one line of code does not compile.

D. Two lines of code do not compile.

6. Which of the following classes is a checked exception?

A. java.lang.Error

B. java.lang.IllegalStateException

C. java.text.ParseException

D. java.lang.RuntimeException

7. How many constructors in WhaleSharkException compile in the following class?

package friendly;public class WhaleSharkException extends Exception { public WhaleSharkException() { super("Friendly shark!"); } public WhaleSharkException(String message) { super(new Exception(new WhaleSharkException())); } public WhaleSharkException(Exception cause) {}}

A. None

B. One

C. Two

D. Three

8. Given the following class diagram, which two classes are missing in the hierarchystarting with the bottom and going upward?

A. IOException, Exception

B. RuntimeException, Exception

C. IllegalArgumentException, RuntimeException

D. IllegalStateException, RuntimeException

9. How many lines of text does the following program print?

package lighting;import java.io.IOException;public class Light { public void turnOn() throws IOException { new IOException("Not ready"); } public static void main(String[] b) throws Exception { try { new Light().turnOn(); } catch (RuntimeException b) { // y1 System.out.println(b); throw new IOException(); // y2 } finally { System.out.println("complete"); } }}

A. One

B. Two


D. The code does not compile because of line y2.

10. Which statement, when inserted into the main() method of a program, guarantees anAssertionError will be thrown at runtime?

A. assert(0,"Invalid");

B. assert 0==1;

C. assert 0==0;



package paper;import java.io.Closeable;public class PrintCompany { class Printer implements Closeable { // r1 public void print() { System.out.println("This just in!"); } public void close() {} } public void printHeadlines() { try {Printer p = new Printer()} { // r2 p.print(); } } public static void main(String[] headlines) { new PrintCompany().printHeadlines(); // r3 }}

A. This just in!

B. The code does not compile because of line r1.


D. The code does not compile because of line r3.

12. Which statement about try-with-resources is not true?

A. If the try block and close() method both throw an exception, the one thrown bythe close() method is suppressed.

B. A catch block is not required.

C. If more than one resource is used, the resources are closed in the order they werecreated.

D. Parentheses are used for the resource declaration section, even if more than oneresource is used.


package bee;class SpellingException extends RuntimeException {}public class SpellChecker { public final static void main(String... participants) { try { if(!"cat".equals("kat")) { new SpellingException(); } } catch (SpellingException | NullPointerException e) { System.out.println("Spelling problem!"); } catch (Exception e) { System.out.println("Unknown Problem!"); } finally { System.out.println("Done!"); } }}

A. One

B. Two

C. Three


14. Which exception classes, when inserted into the blank in the Problems class, allow thecode to compile?

package more;class MissingMoneyException extends Exception {}class MissingFoodException extends Exception {}public class Problems { public void doIHaveAProblem() throws MissingMoneyException, MissingFoodException { System.out.println("No problems"); } public static void main(String[] lots) throws ________________{ try { final Problems p = new Problems(); p.doIHaveAProblem(); } catch (Exception e) { throw e; } }}

I. Exception

II. MissingMoneyException

III. MissingMoneyException, MissingFoodException

A. I only

B. III only

C. I and III

D. I, II, and II

15. Which statement about Closeable and AutoCloseable is true?

A. AutoCloseable extends Closeable.

B. The close() method in a class that implements AutoCloseable cannot throw anIOException.

C. The close() method in a class that implements Closeable cannot throw anException.

D. There is no difference; one was added for backward compatibility.

16. Which expression, when inserted into the blank in the following class, allows the codeto compile?

package sun;import java.io.*;public class Beach { class TideException extends Exception {} public void surf() throws RuntimeException { try { throw new TideException(); } catch (________________) {} }}

A. Exception a | RuntimeException f

B. IllegalStateException | TideException t

C. TideException | IOException i

D. TideException | Exception x

17. Which statement about a multi-catch statement is true?

A. The exception types must be ordered from broadest to narrowest.

B. The exception types must be ordered from narrowest to broadest.

C. The variable of a multi-catch block with more than one exception cannot bereassigned within the block.

D. The variable of a multi-catch block with one exception type cannot be reassignedwithin the block.


package move;interface Closing { void close() throws Exception;}class Shelf implements Closing { public void close() throws Exception {}}

public class Step { static { try (Shelf shelf = new Shelf()) { throws new IllegalArgumentException(); } catch (Exception e) { } catch (IllegalArgumentException e) { } finally { shelf.close(); } }}

A. None

B. Two

C. Three

D. Four

19. Which of the following is not true of using a try-with-resources statement?

A. Associated catch blocks are run before the declared resources have been closed.

B. It is compatible with all classes that implement the AutoCloseable interface.

C. It is compatible with all classes that implement the Closeable interface.

D. It shortens the amount of code a developer must write.

20. Assuming the following application is executed with assertions enabled, what is theresult?

package input;public class DataIntegrity { private int score; public DataIntegrity() { super(); DataIntegrity.this.score = 5; } public static void main(String[] books) { final DataIntegrity johnny5 = new DataIntegrity(); assert(johnny5.score>2) : johnny5.score++; assert johnny5.score>=5 : System.out.print("No input"); System.out.print("Made it!"); }}

A. An AssertionError is thrown with a message of 5.

B. An AssertionError is thrown with a message of No input.

C. Made it! is printed.


21. Which of the following classes is an unchecked exception?

A. java.io.IOException

B. java.io.NotSerializableException

C. java.sql.SQLException

D. java.util.MissingResourceException


package wind;public class Storm { public static void main(String... rain) throws Exception { try (final AutoCloseable weatherTracker = new AutoCloseable() { public void close() throws RuntimeException {} }) { System.out.println(weatherTracker.toString()); } catch (Exception e) { if(weatherTracker != null) { weatherTracker.close(); } } finally { System.out.println("Storm gone"); } }}

A. It prints one line.

B. It prints two lines.

C. It does not compile due to an error in the declaration of the weatherTrackerresource.

D. It does not compile for a different reason.

23. Which of the following is not a command that enables or disables assertions atruntime?

A. -di

B. -disableassertions

C. -ea

D. -enableassertions


package signlanguage;import java.io.Closeable;class ReadSign implements Closeable { public void close() {} public String get() {return "Hello";}}class MakeSign implements AutoCloseable { public void close() {} public void send(String message) {

System.out.print(message); }}public class Translate { public static void main(String... hands) { try (ReadSign r = new ReadSign(); MakeSign w = new MakeSign();) { w.send(r.get()); } }}

A. Hello

B. The code does not compile because of the ReadSign class.

C. The code does not compile because of the try-with-resources statement.



package what;class FunEvent implements AutoCloseable { public void close() { System.out.print("1"); }}public class Happening { public static void main(String... lots) { try (FunEvent f = new FunEvent()) { System.out.print("2"); throw new ArithmeticException(); } catch (Exception e) { System.out.print("3"); } finally { System.out.print("4"); } }}

A. 214

B. 2134

C. 2314


26. Which statement best describes how a class that implements the AutoCloseableinterface should be written?

A. The close() method is optional since the AutoCloseable interface defines adefault implementation.

B. The close() method should avoid modifying data after it has been run once.

C. The close() method should not throw any exceptions.

D. The close() method should return a status code.

27. Which statement about the following program is correct?

package dogpark;public class Fetch { public int play(String dogName) throws Exception { try { throw new RuntimeException(dogName); } catch (Exception e) { throw new RuntimeException(e); } } public static final void main(String[] ball) throws RuntimeException { new Fetch().play("Webby"); new Fetch().play("Georgette"); }}

A. The program prints one exception at runtime.

B. The program prints two exceptions at runtime.

C. The class does not compile because of the play() method.

D. The class does not compile because of the main() method.

28. Which of the following is not a good use of assertions?

A. Check method post conditions.

B. Modify local variables.

C. Test control flow invariants.

D. Validate class invariants.

29. Which statement about the following application is correct?

package highway;import java.io.*;class CarCrash extends RuntimeException {}public class Car { public static void main(String[] seatbelts) throws Exception { // w1 try { throw new IOException("Auto-pilot error"); } catch (Exception | CarCrash e) { // w2 throw e; } catch (Exception a) { // w3 throw a; } }}

A. The code does not compile because of line w1.

B. The code does not compile because of line w2.

C. The code does not compile because of line w3.


30. Which statements about the following classes are true?

public class Dopey extends Grumpy {}public class Grumpy extends Exception {}public class Happy extends IOException {}public class Sleepy extends IllegalStateException {}public class Sneezy extends Throwable {}

I. Four of the classes are checked exceptions.

II. Two of the classes are unchecked exceptions.

III. None of the class declarations contain any compilation errors.

A. I only

B. I and III

C. II and III

D. I, II, and III


package vortex;class TimeException extends Exception {}class TimeMachine implements AutoCloseable { int v; public TimeMachine(int v) {this.v = v;} public void close() throws Exception { System.out.print(v); }}public class TimeTraveler { public static void main(String[] twelve) { try (TimeMachine timeSled = new TimeMachine(1); TimeMachine delorean = new TimeMachine(2); TimeMachine tardis = new TimeMachine(3)) { } catch (TimeException e) { System.out.print(4); } finally { System.out.print(5); } }}

A. 1235

B. 3215

C. 41235


32. Which expression, when inserted into the blank in the following class, allows the codeto compile?

package music;public class Bells { class Player implements AutoCloseable { @Override public void close() throws RingException {} } class RingException extends Exception { public RingException(String message) {} } public static void main(String[] notes) throws Throwable { try (Player p = null) { throw new Exception(); } catch (Exception e) { } catch (_______________) { } }}

A. Error r

B. IllegalStateException b

C. RingException p

D. The code does not compile regardless of the expression used.

33. Given the following two variables, which assertion statement compiles successfully?

int age = 22;final String name = "Josephine";

A. assert (age=2);

B. assert age!=age : (1<age ? "Error" : 10);

C. assert name.equals("") : () -> "Oops";

D. assert name.length()<(long)age : return "Mistake";

34. Which statement about the following program is true?

package tag;class MissedCallException extends Exception {}public class Phone { static void makeCall() throws RuntimeException { throw new ArrayIndexOutOfBoundsException("Call"); } public static void main(String[] messages) { try { makeCall(); } catch (MissedCallException e) { throw new RuntimeException("Voicemail"); } finally { throw new RuntimeException("Text"); } }

}

A. An exception is printed at runtime with Call in the message.

B. An exception is printed at runtime with Voicemail in the message.

C. An exception is printed at runtime with Text in the message.


35. Which statement about the following program is correct?

package fairy;public class Tale { class BearException extends RuntimeException {} class WolfException extends RuntimeException {} class DragonException extends RuntimeException {} public int tellStory() { try {} catch (BearException d) { d = new RuntimeException(); throw d; } catch (WolfException | DragonException e) { e = new RuntimeException(); throw e; } return 3; } public static void main(String... wand) throws RuntimeException{ new Tale().tellStory(); }}

A. The class compiles and does not print anything at runtime.

B. The code does not compile solely due to the first catch block in tellStory().

C. The code does not compile solely due to the second catch block in tellStory().

D. The code does not compile due to errors in both catch blocks in tellStory().


package classical;import java.io.*;class OutOfTuneException extends Exception { OutOfTuneException(String message) { super(message); }}public class Piano { public void play() throws OutOfTuneException, FileNotFoundException { throw new OutOfTuneException("Sour note!"); } public static void main(String... keys) throws OutOfTuneException { final Piano piano = new Piano(); try { piano.play(); } catch (Exception e) { throw e; } finally {

System.out.println("Song finished!"); } }}

A. Song finished!

B. An exception is printed with Sour note! in the stack trace.

C. Both of the above


37. Given the following class, which command causes the class to throw anAssertionError at runtime?

public class Falcon extends Exception { private int parsec = 12; public Falcon(String name) { super(name); } public static void main(String[] aluminum) { assert new Falcon(null).parsec<12; }}

A. java Falcon

B. java -ea -da:Falcon Falcon

C. java -da -ea:Falcon Falcon



package db;import java.io.*;import java.sql.*;public class DatabaseHelper { static class MyDatabase implements Closeable { public void close() throws SQLException { System.out.print("2"); } public void write(String data) {} public String read() {return null;} } public static void main(String... files) throws Exception { try (MyDatabase myDb = new MyDatabase()) { // TODO: Decide what to read/rite } finally { System.out.print("1"); } }}

A. 12

B. 21

C. The code does not compile because of the MyDatabase class.

D. The code does not compile because of the try-with-resources statement.


package tron;class DiskPlayer implements AutoCloseable { public void close() throws Exception {}}public class LightCycle { public static void main(String... bits) { try (DiskPlayer john = new DiskPlayer()) { System.out.println("ping"); } finally { System.out.println("pong"); } System.out.println("return"); }}

A. One

B. Two

C. Three


40. Given the application below, what is the name of the class printed at line e1?

package canyon;final class FallenException extends Exception {}final class HikingGear implements AutoCloseable { @Override public void close() throws Exception { throw new FallenException(); }}public class Cliff { public final void climb() throws Exception { try (HikingGear gear = new HikingGear()) { throw new RuntimeException(); } } public static void main(String... rocks) { try { new Cliff().climb(); } catch (Throwable t) { System.out.println(t); // e1 } }}

A. canyon.FallenException

B. java.lang.RuntimeException


D. The code compiles, but the answer cannot be determined until runtime.

Chapter 17Use Java SE 8 Date/Time APITHE OCP EXAM TOPICS COVERED IN THIS PRACTICE TEST INCLUDETHE FOLLOWING:

Use Java SE 8 Date/Time API

Create and manage date-based and time-based events including a combination ofdate and time into a single object using LocalDate, LocalTime, LocalDateTime,Instant, Period, and Duration

Work with dates and times across timezones and manage changes resulting fromdaylight savings including Format date and times values

Define and create and manage date-based and time-based events using Instant,Period, Duration, and TemporalUnit

1. What package is the LocalTime class in?

A. java.date

B. java.lang

C. java.time

D. java.util

2. How many of the classes Duration, LocalDateTime, and LocalTime have the concept ofa time zone?

A. None

B. One

C. Two

D. Three

3. Which class has a getSeconds() method?

A. Only the Duration class

B. Only the Period class

C. Both the Duration and Period classes

D. Neither class

4. Which of these represents the earliest date/time?

A. 2017-02-15T03:00+01:00[Europe/Berlin]

B. 2017-02-15T04:00+02:00[Europe/Helsinki]

C. 2017-02-15T05:00+01:00[Europe/Warsaw]

D. None of the above. We have a tie.

5. Most of the United States observes daylight savings time on March 12, 2017, bymoving the clocks forward an hour at 2 a.m. What does the following code output?

LocalDate localDate = LocalDate.of(2017, 3, 12);LocalTime localTime = LocalTime.of(1, 0);ZoneId zone = ZoneId.of("America/New_York");ZonedDateTime z = ZonedDateTime.of(localDate, localTime, zone);Duration duration = Duration.ofHours(3);ZonedDateTime later = z.plus(duration);System.out.println(later.getHour());

A. 4

B. 5

C. 6



int year = 1874;int month = Month.MARCH;int day = 24;LocalDate date = LocalDate.of(year, month, day);System.out.println(date.isBefore(LocalDate.now()));

A. false

B. true



7. Which correctly fills in the blank to print 2017-01-15?

LocalDate hatDay = LocalDate.of(2017, Month.JANUARY, 15);DateTimeFormatter f = DateTimeFormatter.ISO_DATE;System.out.println(_______________________);

I. f.format(hatDay)

II. f.formatDate(hatDay)

III. hatDay.format(f)

A. I

B. III

C. I and III

D. II and III

8. Which of the answer choices is true given the following?

2017-01-07T10:00-07:00[America/Phoenix]2017-01-07T08:00-08:00[America/Vancouver]

A. The first date/time is one hour earlier than the second.

B. The first date/time is three hours earlier than the second.

C. The first date/time is one hour later than the second.

D. The first date/time is three hours later than the second.

9. Given that daylight savings time starts on March 12, 2017, at 2 a.m. and clocks jumpfrom 1:59 a.m. to 03:00 a.m., which of the following can fill in the blank so the codedoesn’t throw an exception?

LocalDate localDate = LocalDate.of(2017, 3, 12);LocalTime localTime = LocalTime.of(__________);ZoneId zone = ZoneId.of("America/New_York");ZonedDateTime z = ZonedDateTime.of(localDate, localTime, zone);

A. 2, 0

B. 3, 0

C. Either of the above will run without throwing an exception.

D. Both of these will cause an exception to be thrown.


11: LocalDate waffleDay = LocalDate.of(2017, Month.MARCH, 25);12: Period period = Period.of(1, 6, 3);13: LocalDate later = waffleDay.plus(period);14: later.plusDays(1);15: LocalDate thisOne = LocalDate.of(2018, Month.SEPTEMBER, 28);16: LocalDate thatOne = LocalDate.of(2018, Month.SEPTEMBER, 29);17: System.out.println(later.isBefore(thisOne) + " "18: + later.isBefore(thatOne));

A. false false

B. false true

C. true true


11. What is a possible result of the following?

LocalDate montyPythonDay = LocalDate.of(2017, Month.MAY, 10);LocalDate aprilFools = LocalDate.of(2018, Month.APRIL, 1);Duration duration = Duration.ofDays(1);LocalDate result = montyPythonDay.minus(duration);System.out.println(result + " " + aprilFools.isBefore(result));

A. 2017-05-09 false

B. 2017-05-09 true



12. What is the result of running this code?

12: LocalDate pieDay = LocalDate.of(2017, Month.JANUARY, 23);13: LocalTime midnight = LocalTime.of(0, 0);14: LocalDateTime pieTime = LocalDateTime.of(pieDay, midnight);15:16: DateTimeFormatter f = DateTimeFormatter17: .ofLocalizedDate(FormatStyle.SHORT);18: f.format(pieDay);19: f.format(pieTime);20: f.format(midnight);

A. The code runs successfully.

B. The code throws an exception on line 19.

C. The code throws an exception on line 20.


13. In the United States, daylight savings time ends on November 5th, 2017 at 02:00 a.m.and we repeat the previous hour. What is the output of the following?

import java.time.*; public class FallBack { public static void main(String[] args) { LocalDate localDate = LocalDate.of(2017, Month.NOVEMBER, 5); LocalTime localTime = LocalTime.of(1, 0); ZoneId zone = ZoneId.of("America/New_York"); ZonedDateTime z = ZonedDateTime.of(localDate, localTime, zone); for (int i = 0; i < 6; i++) z.plusHours(1); System.out.println(z.getHour()); }}

A. 5

B. 6

C. 7


14. What format pattern would you pass to a DateTimeFormatter so it creates hour andminute output such as 02:33?

A. HH:MM

B. HH:mm

C. hh:MM

D. hh:mm

15. LocalTime.of() has a number of overloads. Which of the following is not one ofthem?

A. LocalTime.of(int hour, int minute)

B. LocalTime.of(int hour, int minute, int second)

C. LocalTime.of(int hour, int minute, int second, int nanoOfSecond)

D. LocalTime.of(int hour, int minute, int second, int nanoOfSecond, intpicoSeconds)

16. How many of the classes LocalDate, Period, and ZonedDate have a method to getthe year?

A. None

B. One

C. Two

D. Three

17. Which statement is not true about these two variables?

Duration duration = Duration.ofDays(1);Period period = Period.ofDays(1);

A. Both output the same value when calling toString().

B. The Duration object compiles because durations are for smaller units of time.

C. The Period object compiles because periods are for larger units of time.


18. What is a possible output of this code?

LocalTime time = LocalTime.of(1,2,3,4);System.out.println(time);

A. 01:02:03.4

B. 01:02:03.000000004

C. 01/01/1970 01:02:03.4

D. 01/01/1970 01:02:03.000000004


import java.time.*;import java.time.format.*; public class PolarBear { public static void main(String[] args) { LocalDate polarBearDay = LocalDate.of(2017, 2, 27); DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyy dd MMM"); System.out.println(polarBearDay.format(formatter)); }}

A. 2017 27 Jan

B. 2017 27 Feb

C. 2017 Jan 27

D. 2017 Feb 27

20. Which contains a constant named HOURS?

A. ChronoUnit

B. Duration

C. Instant

D. Period

21. The United States observes daylight savings time on March 12, 2017, by moving theclocks forward an hour at 2 a.m. What does the following code output?

LocalDate localDate = LocalDate.of(2017, 3, 12);LocalTime localTime = LocalTime.of(13, 0);ZoneId zone = ZoneId.of("America/New_York");ZonedDateTime z = ZonedDateTime.of(localDate, localTime, zone);Duration duration = Duration.ofHours(3);ZonedDateTime later = z.plus(duration);System.out.println(later.getHour());

A. 13

B. 16

C. 17


22. What is a possible result of the following?

LocalDate montyPythonDay = LocalDate.of(2017, Month.MAY, 10);LocalTime time = LocalTime.of(5, 40);LocalDateTime dateTime = LocalDateTime.of(montyPythonDay, time);Duration duration = Duration.ofDays(1);LocalDateTime result = dateTime.minus(duration);System.out.println(result);

A. 2017-05-09

B. 2017-05-09T05:40

C. 2017-05-10T05:40


23. Which correctly fills in the blank to print 2017-01-15?

LocalDate hatDay = LocalDate.of(2017, Month.JANUARY, 15);DateFormatter f = DateFormatter.ISO_DATE;System.out.println(______________________________);

A. f.format(hatDate)

B. hatDay.format(f)


D. Neither of the above

24. LocalDateTime.of() has a number of overloads. Which of the following is not oneof them?

A. LocalDateTime.of(LocalDate date, LocalTime time)

B. LocalDateTime.of(LocalDate date, int hour, int minute)

C. LocalDateTime.of(int year, int month, int day, int hour, int minute)

D. LocalDateTime.of(int year, Month month, int day, int hour, int minute)

25. In the United States, daylight savings time for 2017 starts at 2 a.m. on March 12th andends at 2 a.m. on November 5th. Given the sequence in the following image, whattime comes next on March 12th, July 4th, and November 5th, respectively?

A. 01:00, 02:00, 01:00

B. 01:00, 02:00, 03:00

C. 03:00, 02:00, 01:00

D. 03:00, 02:00, 03:00


LocalDate date1 = LocalDate.of(2017, Month.MARCH, 3);LocalDate date2 = LocalDate.of(2017, Month.FEBRUARY, 31);System.out.println(date1.equals(date2));

A. false

B. true



27. Given this date/time and time zone offset, what time is it in GMT?

2017-03-09T16:00-10:00[US/Hawaii]

A. 02:00

B. 04:00

C. 06:00

D. 10:00

28. What is a possible output of the following?

LocalDate trainDay = LocalDate.of(2017, 5, 13);LocalTime time = LocalTime.of(10, 0);

ZoneId zone = ZoneId.of("America/Los_Angeles");ZonedDateTime zdt = ZonedDateTime.of(trainDay, time, zone);Instant instant = zdt.toInstant();instant = instant.plus(1, ChronoUnit.DAYS);System.out.println(instant);

A. 2017-05-13T10:00-07:00[America/Los_Angeles]

B. 2017-05-13T17:00:00Z

C. 2017-05-14T10:00-07:00[America/Los_Angeles]

D. 2017-05-14T17:00:00Z


LocalDate date = LocalDate.of(2017, Month.JULY, 17);LocalTime time = LocalTime.of(10, 0);ZoneId zone = ZoneId.of("America/New_York");ZonedDateTime iceCreamDay = ZonedDateTime.of(date, time, zone);time = time.plusMonths(1);System.out.println(iceCreamDay.getMonthValue());

A. 6

B. 7

C. 8



import java.time.*;import java.time.format.*; public class PolarBear { public static void main(String[] args) { LocalDate polarBearDay = LocalDate.of(2017, 2, 27); DateTimeFormatter formatter = DateTimeFormatter .ofPattern("Holiday: yyyy dd MMM"); System.out.println(polarBearDay.format(formatter)); }}

A. Holiday: 2017 27 Jan

B. Holiday: 2017 27 Feb



31. Which of these represents the earliest date/time?

A. 2017-02-15T16:00+07:00[Asia/Bangkok]

B. 2017-02-15T18:00+04:00[Asia/Dubai]

C. 2017-02-15T20:00+08:00[Asia/Kuala_Lumpur]

D. None of the above. We have a tie.


11: LocalDate waffleDay = LocalDate.of(2017, Month.MARCH, 25);12: Period period = Period.ofYears(1).ofMonths(6).ofDays(3);13: LocalDate later = waffleDay.plus(period);14: later.plusDays(1); 15: LocalDate thisOne = LocalDate.of(2018, Month.SEPTEMBER, 28);16: LocalDate thatOne = LocalDate.of(2018, Month.SEPTEMBER, 29);17: System.out.println(later.isBefore(thisOne) + " "18: + later.isBefore(thatOne));

A. false false

B. false true

C. true true


33. How many of the following can fill in the blank so this code compiles and prints 31?

LocalDate xmas = LocalDate.of(2017, 12, 25);LocalDate blackFriday = LocalDate.of(2017, 11, 24);long shoppingDaysLeft =____________________ ;System.out.println(shoppingDaysLeft);

I. blackFriday.until(xmas, ChronoUnit.DAYS)

II. blackFriday.until(xmas, TemporalUnit.DAYS)

III. ChronoUnit.DAYS.between(blackFriday, xmas)

IV. TemporalUnit.DAYS.between(blackFriday, xmas)

A. One

B. Two

C. Three

D. Four

34. How many of these classes cause a compiler error when filling in the blank:LocalDate, LocalDateTime, LocalTime, ZonedDateTime?

private static String formatMe(__________ obj) { DateTimeFormatter f = DateTimeFormatter.ofLocalizedTime(FormatStyle.MEDIUM); return f.format(obj);}

A. None

B. One

C. Two

D. Three


LocalDate date = LocalDate.of(2017, Month.JULY, 17);LocalTime time = LocalTime.of(10, 0);ZoneId zone = ZoneId.of("America/New_York");ZonedDateTime iceCreamDay = ZonedDateTime.of(date, time, zone);date = date.plusMonths(1);System.out.println(iceCreamDay.getMonthValue());

A. 6

B. 7

C. 8


36. Which of the following can fill in the blank to make this code compile?

public boolean isItMyBirthday(LocalDateTime dateTime) { ______________________________ return now.getMonth() == dateTime.getMonth() && now.getDayOfMonth() == dateTime.getDayOfMonth();}

A. LocalDate now = LocalDate.now();

B. LocalDate now = new LocalDate();

C. ZonedDate now = ZonedDate.now();

D. ZonedDate now = new ZonedDate();


LocalDate date1 = LocalDate.of(2017, Month.MARCH, 3);LocalDate date2 = date1.plusDays(2).minusDays(1).minusDays(1);System.out.println(date1.equals(date2));

A. false

B. true




LocalDate date = LocalDate.of(2017, 5, 13);LocalTime time = LocalTime.of(10, 0);LocalDateTime trainDay = LocalDateTime.of(date, time);Instant instant = trainDay.toInstant();instant = instant.plus(1, ChronoUnit.DAYS);System.out.println(instant);


B. 2017-05-14T17:00:00Z




public class PiDay { public static void main(String[] args) { LocalDateTime pi = LocalDateTime.of(2017, 3, 14, 1, 59); DateTimeFormatter formatter = DateTimeFormatter .ofPattern("M.ddhhmm"); System.out.println(formatter.format(pi)); }}

A. 3.140159

B. 59.140103



40. Daylight savings time ends on November 5, 2017 at 2 a.m. when we repeat the hour.Suppose we have a ZonedDateTime that outputs 2017-11-05T01:00-04:00[America/New_York] when calling toString(). What is a possible value of the ZonedDateTimeobtained by adding an hour to this value?

A. 2017-11-05T01:00-04:00[America/New_York]

B. 2017-11-05T02:00-04:00[America/New_York]

C. 2017-11-05T01:00-05:00[America/New_York]

D. 2017-11-05T02:00-05:00[America/New_York]

Chapter 18Java I/O FundamentalsTHE OCP EXAM TOPICS COVERED IN THIS PRACTICE TEST INCLUDE THEFOLLOWING:

Java I/O Fundamentals

Read and write data from the console

Use BufferedReader, BufferedWriter, File, FileReader, FileWriter,FileInputStream, FileOutputStream, ObjectOutputStream, ObjectInputStream, andPrintWriter in the java.io package.

1. Fill in the blanks: Writer is__________ that related stream classes__________ .

A. a concrete class, extend

B. an abstract class, extend

C. an interface, extend

D. an interface, implement

2. Which of the following methods is defined in java.io.File?

A. createDirectory()

B. getLength()

C. listFile()

D. renameTo()

3. Which method in InputStream can be used in place of calling skip(1)?

A. jump()

B. mark()

C. read()

D. reset()

4. Which methods are classes that implement java.io.Serializable required toimplement?

A. deserialize()

B. serial()

C. serialize()


5. Fill in the blanks: Given a valid Console instance, reader() returns a__________ ,while writer() returns a __________.

A. PrintReader, PrintWriter

B. PrintReader, Writer

C. Reader, Writer

D. StringReader, Writer

6. Assuming the file path referenced in the following class is accessible and able to bewritten, what is the output of the following program?

package alarm;import java.io.*;public class Smoke { public void sendAlert(File fn) {

try(BufferedWriter w = new BufferedWriter(new FileOutputStream(fn))) { w.write("ALERT!"); w.flush(); w.write('!'); System.out.print("1"); } catch (IOException e) { System.out.print("2"); } finally { System.out.print("3"); } } public static void main(String[] testSignal) { new Smoke().sendAlert(new File("alarm.txt")); }}

A. 3

B. 13

C. 23


7. Which class is used to read information about a directory within the file system?

A. java.io.File

B. java.io.Directories

C. java.io.Directory

D. java.io.Path

8. Which of the following is a high-level stream class that can only be used to wrap alow-level stream?

A. FileOutputStream

B. FileReader

C. ObjectInputStream

D. PrintWriter

9. Assume the file prime6.txt exists and contains the first six prime numbers as bytes: 2,3, 5, 7, 11, 13. What is the output of the following application?

package numbers;import java.io.*;public class PrimeReader { public static void main(String[] real) throws Exception { try (InputStream is = new FileInputStream("prime6.txt")) { is.skip(1); is.read(); is.skip(1); is.read(); is.mark(4);

is.skip(1); is.reset(); System.out.print(is.read()); } }}

A. 11

B. 13



10. Fill in the blanks: For a given file, the absolute is the path from the __________tothe file, while the relative path is the path from the __________to the file.

A. current directory, current working directory

B. parent directory, temporary directory

C. root directory, current working directory

D. root directory, parent directory

11. Which statement best describes the following two methods?

public void writeSecret1() throws IOException { final Writer w = new BufferedWriter( new FileWriter("dont.open")); w.write("Secret passcode"); w.close();}public void writeSecret2() throws IOException { try(final Writer w = new BufferedWriter( new FileWriter("dont.open"))) { w.write("Secret passcode"); }}

A. Both methods compile and are equivalent to each other.

B. Neither method compiles.

C. Only one of the methods compiles.

D. The methods compile, but one method may lead to a resource leak.

12. What is the result of compiling and executing the following program?

package vacation;import java.io.*;import java.util.*;public class Itinerary { private List<String> activities = new ArrayList<>(); private static Itinerary getItinerary(String name) { return null;

} public static void printItinerary() throws Exception { Console c = new Console(); final String name = c.readLine("What is your name?"); final Itinerary stuff = getItinerary(name); stuff.activities.forEach(s -> c.printf(s)); } public static void main(String[] holidays) throws Exception { printItinerary(); }}


B. The code compiles and prints a NullPointerException at runtime.

C. The code compiles but does not print anything at runtime.


13. Given the following diagram, which two classes can be placed in the blank boxes?

A. BufferedOutputStream and PrintStream

B. BufferedOutputStream and PrintOutputStream

C. ByteArrayOutputStream and Stream

D. FileOutputStream and OutputStream

14. Let’s say we want to write an instance of Cereal to disk, having a name value ofCornLoops. What is the value of name after this object has been read using theObjectInputStream’s readObject() method?

package breakfast;public class Cereal { private String name = "CocoaCookies"; private transient int sugar; public Cereal() { super(); this.name = "CaptainPebbles"; } { name = "SugarPops";

} public String getName() { return name; } public void setName(String name) { this.name = name; } public int getSugar() { return sugar; } public void setSugar(int sugar) { this.sugar = sugar; }}

A. CaptainPebbles

B. CornLoops

C. SugarPops


15. Which statement best describes the difference between a Writer and an OutputStreamclass?

A. Only one of them can write text or character data.

B. Only one of them has built-in methods for writing character data.

C. Only one of them has a flush() method to force the data to be written out.

D. One uses a byte array to process character data more efficiently.

16. What is the output of the following application? It is safe to assume the directoriesreferenced in the class do not exist prior to the execution of the program and that thefile system is available and able to be written.

package job;import java.io.*;public class Resume { public void resetWorkingDirectory() throws Exception { File f1 = new File("/templates/proofs"); f1.mkdirs(); File f2 = new File("/templates"); f2.mkdir(); // k1 new File(f2,"draft.doc").createNewFile(); f1.delete(); f2.delete(); // k2 } public static void main(String... leads) { try { new Resume().resetWorkingDirectory(); } catch (Exception e) { new RuntimeException(e); } }}

A. Line k1 does not compile or triggers an exception at runtime.

B. Line k2 does not compile or triggers an exception at runtime.

C. The code compiles and runs without printing an exception.


17. Given the following class, three of the values ensure it runs properly on variousdifferent systems. Which value does not?

package magic;import java.io.*;public class Store { private final String directory; public Store(String directory) { this.directory = directory; } public File getDatabaseFolder(String file) { return new File(directory + __________ + file); }}

A. java.io.File.separator

B. new File(new String()).separatorChar

C. System.getProperty("file.separator")

D. System.getProperty("path.separator")

18. How many compilation errors does the following class contain?

package hero;import java.io.*;public class Guitar { public void readMusic(File f) { try (BufferedReader r = new BufferedReader(FileReader(f))) { final String music = null; try { while((music = r.readLine()) != null) System.out.println(music); } catch (IOException e) {} } catch (FileNotFoundException e) { throw new RuntimeException(e); } finally {}}}

A. None

B. One

C. Two

D. Three

19. What is the difference between the two Console methods, format() and printf()?

A. One of them takes an optional list of arguments; the other does not.

B. One of them takes String as input; the other takes an Object.

C. There is no difference between the two methods.

D. Trick question! printf() is not defined in Console.

20. Let’s say you want to write a lot of text data to a file in an efficient manner. Which twojava.io stream classes are best to use?

A. FileOutputStream and BufferedOutputStream

B. FileOutputWriter and FileBufferedWriter

C. FileWriter and BufferedWriter

D. ObjectOutputStream and BufferedWriter

21. Assume the file referenced in the StudentManager class exists and contains data.Which statement about the following class is correct?

package school;import java.io.*;class Student implements Serializable {}public class StudentManager { public static void main(String[] grades) { try(ObjectInputStream ios = new ObjectInputStream( new FileInputStream(new File("C://students.data")))) { Student record; while((record = (Student)ios.readObject()) != null) { System.out.print(record); } } catch (EOFException e) { } catch (Exception e) { throw new RuntimeException(e); } }}


B. The code compiles but prints an exception at runtime.

C. The program runs and prints all students in the file.

D. The program runs but may only print some students in the files.

22. Which java.io class does not have a complementary input stream?

A. BufferedOutputStream

B. BufferedWriter

C. FileWriter

D. PrintWriter

23. Assuming the path /Earth does not exist within the file system, what is the output ofthe following program?

package center;import java.io.*;public class Journey { public static void main(String[] dig) { File file = new File("/Earth"); System.out.print(file.getParent() +" - " +file.getParent().getParent()); } }

A. / - /

B. / - null



24. Which statements about executing the following program are true?

package test;import java.io.*;public class Turing { public static void main(String... robots) { Console c = System.console(); final String response = c.readLine("Are you human?"); System.err.print(response); }}

I. The program may ask the user a question and print the response to the errorstream.

II. The program may throw a NullPointerException at runtime.

III. The program may wait indefinitely.

A. I

B. I and III

C. II and III

D. I, II, and III

25. Which of the following statements about the deleteTree() method is correct?

public void deleteTree(File f) { if(!f.isDirectory()) f.delete(); else { Stream.of(f.list()) .forEach(s -> deleteTree(s)); f.deleteDirectory(); }}

A. It compiles and is capable of deleting a directory tree.

B. If one line were modified, it would be capable of deleting a directory tree.

C. If two lines were modified, it would be capable of deleting a directory tree.


26. Which of the following is not a built-in stream in Java?

A. System.err

B. System.in

C. System.info

D. System.out

27. Assuming the file path referenced in the following class is accessible and able to bewritten, what is the output of the following program?

package store;import java.io.*;public class Furniture { public final static void main(String... inventory) throws Exception { Writer w = new FileWriter("couch.txt"); try (BufferedWriter bw = new BufferedWriter(w)) { bw.write("Blue coach on Sale!"); } finally { w.flush(); w.close(); } System.out.print("Done!"); }}

A. Done!

B. The code does not compile for one reason.

C. The code does not compile for two reasons.


28. Given an instance of Console c, which of the following method calls is not a way toread input from the user?

A. c.reader().read()

B. c.reader().readLine()

C. c.readLine()

D. c.readPassword()

29. The copyPidgin() method is used to copy the contents of one file to another. Whichstatement about the implementation is correct?

package birds;import java.io.*;

public class Pidgin { public void copyPidgin(File s, File t) throws Exception { try(InputStream is = new FileInputStream(s); OutputStream os = new FileOutputStream(t)) { byte[] data = new byte[123]; int chirps; while((chirps = is.read(data))>0) { os.write(data); }} }}

A. The class does not compile because read(byte[]) and write(byte[]) can only becalled on BufferedInputStream and BufferOutputStream, respectively.

B. The method correctly copies the contents of all files.

C. The method correctly copies the contents of some files.

D. The method will always throw an exception at runtime because the data array sizeis not a power of 2.

30. Using what you know about java.io stream class names, what would a nonexistentclass named BufferedFileReader most likely be used for?

A. Reading a small text file from a remote network

B. Reading an image from disk

C. Reading large text files from a file system

D. Reading serialized data from disk


package factory;import java.io.*;public class WidgetProcessor { public int getWidgetNumber(byte[] data) throws Exception { try (InputStream is = new ByteArrayInputStream(data)) { is.read(new byte[2]); if(!is.markSupported()) return -1; is.mark(5); is.read();is.read(); is.skip(3); is.reset(); return is.read(); } } public static void main(String... sprockets) throws Exception { final WidgetProcessor p = new WidgetProcessor(); System.out.print(p.getWidgetNumber(new byte[] {1,2,3,4,5,6,7})); }}

A. 3

B. 5

C. 7

D. An exception is thrown at runtime.

32. Assuming the working directory is accessible, empty, and able to be written, how manyfile system objects does the following class create?

1: package kitchen;2: import java.io.*;3: public class Bakers {4: public static void main(String... tooMany) throws IOException {5: File cake = new File("cake.txt");6: Writer pie = new FileWriter("pie.txt");7: pie.flush();8: new File("fudge.txt").mkdirs();9: } }

A. None

B. One

C. Two

D. Three

33. Let’s say you wanted to read data from a file stored on disk that consists of String,long, and Object values? Given that the file is quite large, you intend to use threeclasses to achieve this result. Which of the following is not one of the three classesyou should use?

A. BufferedInputStream

B. BufferedReader

C. FileInputStream

D. ObjectInputStream

34. Which statement best describes the following two methods?

public String getNameQuick() throws IOException { final BufferedReader r = new BufferedReader( new FileReader("saved.name")); final String name = r.readLine(); r.flush(); return name;}public String getNameSafely() throws IOException { try(final BufferedReader r = new BufferedReader( new FileReader("saved.name"))) { final String name = r.readLine(); r.flush(); return name;}}

A. Both methods compile and are equivalent to each other.

B. Neither method compiles.

C. Only one of the methods compiles.

D. The methods compile, but one method may lead to a resource leak.

35. What is the output of the following application? Assume the System.console() isavailable and the user enters badxbad and presses Enter.

package hardway;import java.io.*;public class InconvenientImplementation { public static void main(String... dontDoThis) throws Exception { Console c = System.console(); if(c != null) { c.writer().write('P'); c.writer().write('a'); c.writer().write('s'); c.writer().write('s'); c.writer().flush(); // t1 int i; StringBuilder sb = new StringBuilder(); while((i = c.reader().read()) != 'x') { // t2 sb.append((char)i); } c.writer().format("Result: %s",sb.toString()); } }}

A. Result: bad

B. Line t1 does not compile or triggers an exception at runtime.

C. Line t2 does not compile or triggers an exception at runtime.


36. Why does Console readPassword() return a char array rather than a String?

A. It improves performance.

B. It improves security.

C. Passwords must be stored as a char array.

D. String cannot hold the individual password characters.

37. Which statement about the following program is true?

package mystical;import java.io.*;public class Unicorn { public void findUnicorns() { try(InputStream o = new ObjectInputStream(readBook())) { while(o.read() != -1) { System.out.println(o.read()); }

} catch (Throwable t) { throw new RuntimeException(t); } } private InputStream readBook() throws IOException { return new BufferedInputStream(new FileReader("magic.book")); } public static void main(String... horn) { new Unicorn().findUnicorns(); }}


B. The program prints every byte in the file without throwing an exception.

C. The program prints every other byte in the file without throwing an exception.

D. The program throws an EOFException when the end of the file is reached.

38. Choose the class that is least likely to be marked Serializable.

A. A class that holds data about the amount of rain that has fallen in a given year

B. A class that manages the memory of running processes in an application

C. A class that stores information about apples in an orchard

D. A class that tracks the amount of candy in a gumball machine


package cell;import java.io.*;public class TextMessage { public String receiveText() throws Exception { try (Reader r = new FileReader("messages.txt")) { StringBuilder s = new StringBuilder(); int c; while((c = r.read()) != -1) { s.append((char)c); if(r.markSupported()) { r.mark(100); r.skip(10); r.reset(); } } return s.toString(); } } public void sendText(String message) throws Exception { try (Writer w = new FileWriter("messages.txt")) { for(int i=0; i<message.length(); i++) { w.write(message.charAt(i)); w.skip(1); } } }

public static void main(String[] minutes) throws Exception { final TextMessage m = new TextMessage(); m.sendText("You up?"); System.out.println(m.receiveText()); } }

A. You up?

B. Y o u u p ?

C. The code does not compile because of the receiveText() method.

D. The code does not compile because of the sendText() method.

40. What is the output of the following program? Assume the file paths referenced in theclass exist and are able to be written to and read from.

package heart;import java.io.*;public class Valve implements Serializable { private int chambers = -1; private transient Double size = null; private static String color; public Valve() { this.chambers = 3; color = "BLUE"; } public static void main(String[] love) throws Throwable { try (ObjectOutputStream o = new ObjectOutputStream( new FileOutputStream("scan.txt"))) { final Valve v = new Valve(); v.chambers = 2; v.size = 10.0; v.color = "RED"; o.writeObject(v); } new Valve(); try (ObjectInputStream o = new ObjectInputStream( new FileInputStream("scan.txt"))) { Valve v = (Valve)o.readObject(); System.out.print(v.chambers+","+v.size+","+v.color); } } { chambers = 4; }}

A. 2,null,RED

B. 2,null,BLUE

C. 3,10.0,RED


Chapter 19Java File I/O (NIO.2)THE OCP EXAM TOPICS COVERED IN THIS PRACTICE TEST INCLUDE THEFOLLOWING:

Java File I/O (NIO.2)

Use Path interface to operate on file and directory paths

Use Files class to check, read, delete, copy, move, manage metadata of a file ordirectory

Use Stream API with NIO.2

1. Fill in the blanks: A(n)__________ is a file that contains a reference to another fileor directory, while a(n)__________ is a file that contains content.

A. irregular file, regular file

B. regular file, opaque file

C. symbolic link, regular file

D. symbolic link, symbolic directory

2. Which methods listed below are found in the NIO.2 Path interface?

I. getRoot()

II. isDirectory()

III. listFiles()

IV. toRealPath()

A. I only

B. I, II, and III

C. I and IV

D. II and III

3. Assuming the file /secret/hide.txt exists and is marked hidden, what is result ofexecuting the following program?

package hidden;import java.nio.file.*;public class Finder { public void findHiddenFile(Path p) throws Exception { if(File.isHidden(p)) { System.out.print("Found!"); } } public static void main(String[] folders) throws Exception { final Finder f = new Finder(); f.findHiddenFile(Paths.get("/secret/hide.txt")); }}

A. The class does not compile.

B. An exception is printed at runtime.

C. Found! is printed at runtime.

D. Nothing is printed at runtime.

4. Fill in the blanks: Files.walk() performs a __________ traversal, whileFiles.find() performs a __________ traversal.

A. breadth-first, breadth-first

B. breadth-first, depth-first

C. depth-first, breadth-first

D. depth-first, depth-first

5. When reading file information, what is an advantage of using an NIO.2 attributeinterface rather than reading the values individually from Files methods?

A. Costs fewer round-trips to the file system

B. Guarantees performance improvement

C. Has support for symbolic links

D. Reduces memory leaks

6. What is the result of compiling and executing the following program? Assume thecurrent directory is /stock and the path /stock/sneakers does not exist prior toexecution.

package shoe;import java.io.*;import java.nio.file.*;public class Sneaker { public void setupInventory(Path desiredPath) throws Exception { Path suggestedPath = Paths.get("sneakers"); if(Files.isSameFile(suggestedPath, desiredPath) // j1 && !Files.exists(suggestedPath)) Files.createDirectories(desiredPath); // j2 } public static void main(String[] socks) throws Exception { Path w = new File("/stock/sneakers").toPath(); // j3 new Sneaker().setupInventory(w); }}

A. The directory /stock/sneakers is created.

B. Line j1 does not compile or produces an exception at runtime.

C. Line j2 does not compile or produces an exception at runtime.

D. Line j3 does not compile or produces an exception at runtime.

7. Assuming the path referenced below exists and contains a symbolic link thatreferences /again, what is the expected result of executing the following code snippet?

System.out.print(Files.walk(Paths.get("/again/and/again")).count());

A. An exception is thrown at runtime.

B. A number is printed at runtime.

C. The process hangs indefinitely.

D. The result cannot be determined with the information given.

8. Which method in the NIO.2 Files class is equivalent to the java.io.File methodlength()?

A. length()

B. size()

C. getLength()


9. Assuming the current working directory is /home, then what is the output of thefollowing program?

1: package magic;2: import java.nio.file.*;3: public class Magician {4: public String doTrick(Path path) {5: return path.subpath(2,3)6: .getName(1)7: .toAbsolutePath()8: .toString();9: }10: public static void main(String... cards) {11: final Magician m = new Magician();12: System.out.print(m.doTrick(13: Paths.get("/bag/of/tricks/.././disappear.txt")));14: } }

A. /home/tricks

B. /home



10. Which methods listed below are found in the NIO.2 Files class?

I. isSameFile()

II. length()

III. relativize()

IV. mkdir()

A. I only

B. I, II, and IV

C. II and III

D. IV only

11. The following code snippet, which attempts to move a file system record fromoldHardDrivePath to newHardDrivePath, results in an exception at runtime. Which ofthe following is the most likely type of exception to be thrown?

Files.move(oldHardDrivePath,newHardDrivePath,REPLACE_EXISTING);

A. AtomicMoveNotSupportedException

B. DirectoryNotEmptyException

C. FileAlreadyExistsException

D. None of the above since the line of code does not compile

12. Which of the following can be filled into the blank that would allow the method tocompile?

public String getPathName(String fileName) { final Path p = ____________________; return p.getFileName();}

I. new File(fileName).toPath()

II. new Path(fileName)

III. FileSystems.getDefault().getPath(fileName)

A. I and II

B. I and III

C. II



package clone;import java.io.*;import java.nio.file.*;public class Rewriter { public static void copy(Path source, Path target) throws Exception { try (BufferedReader r = Files.newBufferedReader(source); Writer w = Files.newBufferedWriter(target)) { String temp = null; while((temp = r.readLine()) != null) { w.write(temp); } } } public static void main(String[] tooMany) throws Throwable { Rewriter.copy(Paths.get("/original.txt"), FileSystems.getDefault().getPath("/","unoriginal.txt")); }}

A. The class compiles without issue.

B. The class never throws an exception at runtime.

C. The implementation correctly copies a regular file.

D. All of the above

14. Fill in the blanks: The Files.__________ method returns a List, while theFiles.__________ method returns a Stream.

A. lines(), readAllLines()

B. lines(), readLines()

C. readAllLines(), lines()

D. readLines(), lines()


1: package yellow;2: import java.nio.file.*;3: public class Road {4: public boolean findHome() {5: Path oftenTraveled = Paths.get("/highway/street/spot.txt");6: Path lessTraveled = Paths.get("/highway/street/house/../.");7: lessTraveled.resolve("spot.txt");8: return oftenTraveled.equals(lessTraveled.normalize());9: }10: public static void main(String... emerald) {11: System.out.print("AM I HOME? "12: +(new Road().findHome() ? "yes" : " no"));13: }14: }

A. AM I HOME? no

B. AM I HOME? yes

C. The class does not compile.

D. The class compiles but throws an exception at runtime.

16. Which of the following is not an advantage of using an NIO.2 Path instead of ajava.io.File to work with files?

A. Contains built-in support for symbolic links

B. Has ability to read operating-system-specific attributes

C. Provides a single method for deleting a directory tree

D. Provides efficient access of file metadata

17. What is the result of executing the following program? Assume the path /drivewayexists and is non-empty, and the directory tree is fully accessible within the filesystem.

package weather;import java.io.*;import java.nio.file.*;public class Snow { public static boolean removeSnow(Path flake) throws IOException {

if(!Files.isDirectory(flake) && !Files.isSymbolicLink(flake)) return Files.delete(flake); else return true; } public static void main(String[] cones) throws IOException { File driveway = new File("/driveway"); for(File f : driveway.listFiles()) { System.out.println(removeSnow(f.toPath())); } }}

A. The program prints a list of only true values.

B. The program prints a mix of true and false values.



18. Which interface name inserted into the blank below allows the code snippet tocompile?

Path file = Paths.get("/data/movie.txt");BasicFileAttributes b = Files.readAttributes(file, __________);

A. BasicFileAttributes.class

B. DosFileAttributes.class

C. PosixFileAttributes.class

D. All of the above

19. What is the output of the following code snippet? Assume that the current directory isthe root path.

Path p1 = Paths.get("./locks");Path p2 = Paths.get("/found/red.zip");System.out.println(p1.relativize(p2));System.out.println(p2.relativize(p1));

A. ../found/red.zip../../locks

B. ../../locks../found/red.zip

C. locks/../found/red.zip../found/locks


20. What is the output of the following code snippet? Assume that the current directory isthe root path.

Path p1 = Paths.get("./found/../keys");Path p2 = Paths.get("/lost/blue.txt");System.out.println(p1.resolve(p2));System.out.println(p2.resolve(p1));

A. /lost/blue.txt./found/../keys

B. /found/../keys/./lost/blue.txt/lost/blue.txt/keys

C. /lost/blue.txt/lost/blue.txt/./found/../keys


21. What is the output of the following application? Assume the application is called witha valid path that exists and is accessible within the file system.

package charity;import java.nio.file.*;public class Roster { protected void printRoster(Path p) { for(Path f : Files.list(p)) { // n1 if(f.toString().endsWith(".per")) // n2 System.out.print(f); } } public static void main(String... volunteers) { new Roster().printRoster(Paths.get(volunteers[0])); }}

A. A list of file names is printed at runtime.

B. The class does not compile due to line n1.

C. The class does not compile due to line n2.


22. Given the following file system diagram, in which forward is a symbolic link to thejava directory, which value does not print /java/Sort.java at runtime?

Path p = Paths.get("/", "objC", "bin");System.out.println(p.resolve("__________").toRealPath());

A. ../backwards/../forward/Sort.java

B. ../forward/./Sort.java

C. ../java/./forward/Sort.java

D. ../../java/Sort.java

23. Using the file system diagram from the previous question, including the symbolic linkfrom forward to java, how many calls to Files.delete() would need to be madebefore the following line could be executed without throwing an exception?

Files.delete(Paths.get("/objC"));

A. One

B. Four

C. Seven

D. None of the above. The symbolic link needs to be removed withFiles.deleteSymbolicLink() first.

24. Assuming the course.txt file exists and is readable, what is the result of executing thefollowing application?

package schoolwork;import java.io.*;import java.nio.file.*;public class Notes { public void printNotes() { try (OutputStream out = System.out) { // y1 Files.copy(out, Paths.get("course.txt")); } catch (IOException e) { throw new RuntimeException(e); } }

public static void main(String[] coursework) { new Notes().printNotes(); }}

A. The code compiles but prints an exception at runtime.

B. The class does not compile due to line y1.

C. The code does not compile for some other reason.

D. The program prints the contents of the course.txt file.

25. When reading file information, what is an advantage of loading aBasicFileAttributeView over a BasicFileAttributes?

A. Allows the hidden attribute to be set

B. Allows the last modified date to be changed

C. All of the file information is read in a single round-trip.

D. There is no advantage.

26. The Rose application is run with an input argument of /flower. The /flower directorycontains five subdirectories, each of which contains five files. How many Path valuesdoes the following application print?

import java.nio.file.*;public class Rose { public void tendGarden(Path p) throws Exception { Files.walk(p,1) .map(p -> p.toRealPath()) .forEach(System.out::println); } public static void main(String... thorns) throws Exception { new Rose().tendGarden(Paths.get(thorns[0])); }}

A. None

B. One

C. Six

D. Thirty-one

27. Which of the following statements, when run independently, produces aNullPointerException at runtime?

I. Paths.get("../sang").getParent().getParent()

II. Paths.get("/sing").getParent().getRoot()

III. Paths.get("/song").getRoot().getRoot()

IV. Paths.get("../sung").getRoot().getParent()

A. I and III

B. I and IV

C. II and III

D. IV only

28. Which statement about the following Finalize class is correct?

1: package end;2: import java.nio.file.*;3: public class Finalize {4: public Path makeAbsolute(Path p) {5: if(p!=null && !p.isAbsolute())6: return p.toAbsolutePath();7: return p;8: }9: }

A. It does not compile because IOException is neither handled nor declared.

B. It does not compile for some other reason.

C. The method compiles and returns a Path value that is always equivalent to theinput argument.

D. The method compiles and returns a Path value that may not be equivalent to theinput argument.

29. Which of the following is a difference between the createDirectory() andcreateDirectories() methods found in the NIO.2 Files class?

A. One takes multiple Path arguments; the other does not.

B. One throws an exception if a file already exists at the directory path; the other doesnot.

C. One declares a checked exception; the other does not.

D. One creates a single directory while the other may create many directories.

30. Assuming the current working directory is /hail, what is the expected output ofexecuting the following code snippet?

Path w1 = Paths.get("../jungle/.././rain..") .toAbsolutePath().normalize();System.out.print(w1.resolve("snow.txt"));

A. /jungle/snow.txt

B. /hail/rain../snow.txt

C. /rain../snow.txt

D. An exception is printed at runtime.


package med;import java.nio.file.*;public class Surgeon { public Path rebuild(Path p) { Path v = null; for(int i=0; i<p.getNameCount(); i++) if(v==null) v = p.getName(i); else v = v.resolve(p.getName(i)); return v; } public static void main(String... tools) { final Surgeon al = new Surgeon(); Path original = Paths.get("/tissue/heart/chambers.txt"); Path repaired = al.rebuild(original); System.out.print(original.equals(repaired)); }}

A. false

B. true



32. Under which circumstances does Files.deleteIfExists() not throw an exception?

A. The file system suddenly becomes unavailable.

B. The path does not exist.

C. The path represents a non-empty directory.

D. The process does not have write access to a path.

33. What is the output of the following code snippet? Assume all referenced paths existwithin the file system.

Path v1 = Path.get("/./desert/./").resolve(Paths.get("sand.doc"));Path v2 = new File("/desert/./cactus/../sand.doc").toPath();System.out.print(Files.isSameFile(v1,v2));System.out.print(" "+v1.equals(v2));System.out.print(" "+v1.normalize().equals(v2.normalize()));

A. false false false

B. true false true

C. true true true



public class Song {

public static void organize(Path folder, Path file) throws IOException { Path p = folder.resolve(file); BasicFileAttributeView vw = Files.getFileAttributeView(p, BasicFileAttributes.class); if(vw.creationTime().toMillis()<System.currentTimeMillis()) { vw.setTimes(FileTime.fromMillis(System.currentTimeMillis()), null,null); } } public static void main(String[] audio) throws Exception { Song.organize(Paths.get("/", "pub"),new File("/songs").toPath()); }}

A. None

B. One

C. Two

D. Three


package stars;import java.nio.file.*;public class Sun { public void printInfo() { Path halleysComet = Paths.get("stars/./rocks/../m1.meteor") .normalize(); Path lexellsComet = Paths.get("./stars/../solar/"); lexellsComet = lexellsComet.subpath(0, 2) .resolve("m1.meteor") .normalize(); System.out.print(halleysComet.equals(lexellsComet) ? "Same!" : "Different!"); } public static void main(String... emerald) { Sun s = new Sun(); s.printInfo(); }}

A. Different!

B. Same!

C. The class does not compile.

D. The class compiles but throws an exception at runtime.

36. Assuming the directory /eclipse/projects exists and its contents are accessible,which statement about the following code snippet is correct?

Path p = Paths.get("/eclipse/projects"); Files.walk(p) .map(z -> z.toAbsolutePath().toString())

.filter(s -> s.endsWith(".java")) .collect(Collectors.toList()).forEach(System.out::println); Files.find(p,Integer.MAX_VALUE, (w,a) -> w.toAbsolutePath().toString().endsWith(".java")) .collect(Collectors.toList()).forEach(System.out::println);

A. The first stream statement does not compile.

B. The second stream statement does not compile.

C. Both statements compile but are unlikely to print the same results at runtime.


37. Assuming the file referenced below exists and is significantly large, which statementabout the following program is correct?

public class SpeedRead { public void jenniferReads(Path p) { Files.lines(p); } public void jonReads(Path p) { Files.readAllLines(p); } public static void main(String[] pages) { Path p = Paths.get("/bookshelf/mobydick.txt"); final SpeedRead r = new SpeedRead(); r.jenniferReads(p); r.jonReads(p); }}


B. The method jenniferReads() is likely to take longer to run.

C. The method jonReads() is likely to take longer to run.

D. It is not possible to know which method will take longer to run.

38. What is the result of executing the following program? Assume the files referenced inthe application both exist and are fully accessible within the file system.

package duplicate;import static java.nio.file.StandardCopyOption.*;import static java.nio.file.Files.*;import java.io.*;import java.nio.file.*;public class CopyOfACopy { public void main(String[] items) throws Exception { final Path s = new File("apples.zip").toPath(); final Path t = FileSystems.getDefault().getPath("oranges.zip"); copy(s,t,REPLACE_EXISTING); // q1 copy(Files.newBufferedReader(t),t,ATOMIC_MOVE); // q2 }}

A. Line q1 does not compile.

B. Line q1 produces an exception at runtime.

C. Line q2 does not compile.

D. Line q2 produces an exception at runtime.

39. Which of the following Files methods requires the enclosing method to handle ordeclare a checked exception?

A. exists()

B. isDirectory()

C. isSameFile()

D. isSymbolicLink()

40. What is the output of the following application? Assume /all-data exists and isaccessible within the file system.

package numbers;import java.nio.file.*;import java.util.stream.Stream;public class TheCount { public static Stream<String> readLines(Path p) { try { return Files.lines(p); } catch (Exception e) { throw new RuntimeException(e); } } public static long count(Path p) throws Exception { return Files.list(p) .filter(w -> Files.isRegularFile(w)) .flatMap(s -> readLines(s)) .count(); } public final static void main(String[] day) throws Exception { System.out.print(count(Paths.get("/all-data"))); }}

A. The number of lines in all files in a directory tree

B. The number of lines in all files in a single directory



Chapter 20Java ConcurrencyTHE OCP EXAM TOPICS COVERED IN THIS PRACTICE TEST INCLUDETHE FOLLOWING:

Java Concurrency

Create worker threads using Runnable, Callable and use an ExecutorService toconcurrently execute tasks

Identify potential threading problems among deadlock, starvation, livelock, andrace conditions

Use synchronized keyword and java.util.concurrent.atomic package to control theorder of thread execution

Use java.util.concurrent collections and classes including CyclicBarrier andCopyOnWriteArrayList

Use parallel Fork/Join Framework

Use parallel Streams including reduction, decomposition, merging processes,pipelines and performance.

1. Which of the following methods is not available on an ExecutorService instance?

A. execute(Callable)

B. execute(Runnable)

C. submit(Callable)

D. submit(Runnable)

2. Which statements about executing the following TicketTaker application multipletimes are true?

package performance;import java.util.concurrent.atomic.*;import java.util.stream.*;public class TicketTaker { long ticketsSold; final AtomicInteger ticketsTaken; public TicketTaker() { ticketsSold = 0; ticketsTaken = new AtomicInteger(0); } public void performJob() { IntStream.iterate(1, p -> p+1) .parallel() .limit(10) .forEach(i -> ticketsTaken.getAndIncrement()); IntStream.iterate(1, q -> q+1) .limit(5) .parallel() .forEach(i -> ++ticketsSold); System.out.print(ticketsTaken+" "+ticketsSold); } public static void main(String[] matinee) { new TicketTaker().performJob(); }}

I. The class compiles and runs without throwing an exception.

II. The first number printed is consistently 10.

III. The second number printed is consistently 5.

A. I only

B. I and II

C. I, II, and III


3. Which of the following is a recommended way to define an asynchronous task?

A. Create a Callable expression and pass it to an instance of Executors.

B. Create a class that extends Thread and overrides the start() method.

C. Create a Runnable expression and pass it to a Thread constructor.

D. All of the above

4. Let’s say you needed a thread executor to create tasks for a CyclicBarrier that has abarrier limit of five threads. Which static method in ExecutorService should you useto obtain it?

A. newSingleThreadExecutor()

B. newSingleThreadScheduledExecutor()

C. newCachedThreadPool()

D. None of these would work.

5. Given the original array, how many of the following for statements result in anexception at runtime, assuming each is executed independently?

List<Integer> original = new ArrayList<>(Arrays.asList(1,2,3,4,5)); List<Integer> copy1 = new CopyOnWriteArrayList<>(original);for(Integer w : copy1) copy1.remove(w); List<Integer> copy2 = Collections.synchronizedList(original);for(Integer w : copy2) copy2.remove(w); List<Integer> copy3 = new ArrayList<>(original);for(Integer w : copy3) copy3.remove(w); Queue<Integer> copy4 = new ConcurrentLinkedQueue<>(original);for(Integer w : copy4) copy4.remove(w);

A. Zero

B. One

C. Two

D. Three

6. Fill in the blanks: __________ is a special case of __________, in which two ormore active threads try to acquire the same set of locks and are repeatedlyunsuccessful.

A. Deadlock, livelock

B. Deadlock, resource starvation

C. Livelock, resource starvation

D. Resource starvation, race conditions


1: package office;2: import java.util.concurrent.*;3: public class TpsReport {4: public void submitReports() {5: ExecutorService service = Executors.newCachedThreadPool();6: Future bosses = service.submit(() -> System.out.print(""));7: service.shutdown();8: System.out.print(bosses.get());9: }10: public static void main(String[] memo) {11: new TpsReport().submitReports();12: }13: }

A. null


C. Line 7 throws an exception at runtime.

D. Line 8 throws an exception at runtime.

8. Which of the following static methods does not exist in the Executors class?

A. newFixedScheduledThreadPool()

B. newFixedThreadPool()

C. newSingleThreadExecutor()

D. newSingleThreadScheduledExecutor()

9. How many times does the following application print Ready at runtime?

package parade;import java.util.concurrent.*;public class CartoonCat { private void await(CyclicBarrier c) { try { c.await(); } catch (Exception e) {} } public void march(CyclicBarrier c) { ExecutorService s = Executors.newSingleThreadExecutor(); for(int i=0; i<12; i++) s.execute(() -> await(c)); s.shutdown(); } public static void main(String... strings) { new CartoonCat().march(new CyclicBarrier(4, () -> System.out.println("Ready"))); }}

A. Zero

B. One

C. Three


10. Which thread-safe class would you use to add elements to the front and back of anordered data structure and includes methods for waiting a specified amount of time todo so?

A. BlockingDeque

B. ConcurrentLinkedDeque

C. ConcurrentSkipListSet

D. LinkedBlockingDeque

11. Three of the four methods below always produce the same result whether they areexecuted on a serial or parallel ordered stream. Which one does not?

A. findAny()

B. findFirst()

C. limit()

D. skip()

12. What is the result of executing the following application multiple times?

package bears;import java.util.*;public class Bounce { public static void main(String... legend) { Arrays.asList(1,2,3,4).stream() .forEach(System.out::println); Arrays.asList(1,2,3,4).parallel() .forEachOrdered(System.out::println); }}

A. Only the first array is printed in the same order every time.

B. Only the second array is printed in the same order every time.

C. Both arrays are printed in the same order every time.


13. Fill in the blanks: In the fork/join framework, using the __________ class requiresoverriding an abstract compute() method containing a generic return type, while usingthe __________ class requires overriding an abstract compute() method containinga void return type.

A. ForkJoinTask, RecursiveAction

B. RecursiveAction, RecursiveTask

C. RecursiveTask, ForkJoinTask

D. RecursiveTask, RecursiveAction

14. Given the following code snippet, which lambda expression is the best choice for theaccumulator, based on the rules for applying a parallel reduction?

public class GoodAccumulator { int i; public void test() { BiFunction<Integer,Integer,Integer> accumulator = _________________; System.out.print(Arrays.asList(1,2,3,4,5) .parallelStream() .reduce(0,accumulator,(s1, s2) -> s1 + s2)); }}

A. (a,b) -> (a-b)

B. (a,b) -> 5

C. (a,b) -> i++

D. None of the above are appropriate.


Callable c = new Callable() { public Object run() {return 10;}};ExecutorService s = Executors.newScheduledThreadPool(1);for(int i=0; i<10; i++) { Future f = s.submit(c); f.get();}s.shutdown();System.out.print("Done!");

A. Done!


C. The code hangs indefinitely at runtime.

D. The code throws an exception at runtime.

16. The following diagrams represent the order of read/write operations of two threadssharing a common variable. Each thread first reads the value of the variable frommemory and then writes a new value of the variable back to memory. Which diagramdemonstrates proper synchronization?

A.

B.

C.

D.


package story;import java.util.*;import java.util.concurrent.*;public class Race { static ExecutorService service = Executors.newFixedThreadPool(8); public static int sleep() { try { Thread.sleep(1000); } catch (Exception e) {} return 1; } public static void hare() { try { Callable c = () -> sleep(); final Collection<Callable<Integer>> r = Arrays.asList(c,c,c); List<Future<Integer>> results = service.invokeAll(r); System.out.println("Hare won the race!"); } catch (Exception e) {e.printStackTrace();} } public static void tortoise() { try { Callable c = () -> sleep(); final Collection<Callable<Integer>> r = Arrays.asList(c,c,c); Integer result = service.invokeAny(r); System.out.println("Tortoise won the race!"); } catch (Exception e) {e.printStackTrace();} } public static void main(String[] p) throws Exception { service.execute(() -> hare()); service.execute(() -> tortoise()); }}

A. Hare won the race! is printed first.

B. Tortoise won the race! is printed first.


D. The result is unknown until runtime.

18. Which of the following concurrent collections is sorted?

A. ConcurrentLinkedQueue

B. ConcurrentSkipListMap

C. CopyOnWriteArrayList

D. LinkedBlockingQueue

19. What is the most likely result of executing the following application?

package unknown;import java.util.concurrent.*;public class Riddle { public void sleep() { try { Thread.sleep(5000); } catch (Exception e) {} } public String getQuestion(Riddle r) { synchronized { sleep(); if(r != null) r.getAnswer(null); return "How many programmers does it take " + "to change a light bulb?"; } } public synchronized String getAnswer(Riddle r) { sleep(); if(r != null) r.getAnswer(null); return "None, that's a hardware problem"; } public static void main(String... ununused) { final Riddle r1 = new Riddle(); final Riddle r2 = new Riddle(); ExecutorService s = Executors.newFixedThreadPool(2); s.submit(() -> r1.getQuestion(r2)); s.execute(() -> r2.getAnswer(r1)); s.shutdown(); }}

A. A deadlock is produced at runtime.

B. A livelock is produced at runtime.

C. The application completes successfully.


20. Which ScheduledExecutorService method can result in the same action beingexecuted by two threads at the same time?

A. scheduleAtFixedDelay()

B. scheduleAtFixedRate()

C. scheduleWithFixedDelay()

D. There is no such method in ScheduledExecutorService.


package olympics;import java.util.concurrent.*;public class Athlete { int stroke = 0; public synchronized void swimming() { stroke++; } public static void main(String... laps) { ExecutorService s = Executors.newFixedThreadPool(10); Athlete a = new Athlete(); for(int i=0; i<1000; i++) { s.execute(() -> a.swimming()); } s.shutdown(); System.out.print(a.stroke); }}

A. 1000


C. The result is unknown until runtime because stroke is not accessed in a thread-safe manner and a write may be lost.

D. The result is unknown until runtime for some other reason.

22. Which of the following is most likely to be caused by a race condition?

A. A thread perpetually denied access to a resource

B. An int variable incorrectly reporting the number of times an operation wasperformed

C. Two threads actively trying to restart a blocked process that is guaranteed to alwaysend the same way

D. Two threads endlessly waiting on each other to release shared locks


package farm;import java.util.concurrent.*;public class CountSheep extends RecursiveAction { static int[] sheep = new int[] {1,2,3,4}; final int start; final int end; int count = 0; public CountSheep(int start, int end) { this.start = start;

this.end = end; } public void compute() { if(end-start<2) { count+=sheep[start]; return; } else { int middle = start + (end-start)/2; invokeAll(new CountSheep(start,middle), new CountSheep(middle,end)); } } public static void main(String[] night) { ForkJoinPool pool = new ForkJoinPool(); CountSheep action = new CountSheep(0,sheep.length); pool.invoke(action); pool.shutdown(); System.out.print(action.count); }}

A. 0

B. 10



24. Which statement about parallel streams is correct?

A. A parallel stream always executes all stream operations faster than a serial stream.

B. A parallel stream always executes certain stream operations faster than a serialstream.

C. A parallel stream synchronizes its operations so that they are atomic.

D. All streams can be converted to a parallel stream.

25. What is a possible output of the following application?

package salvage;import java.util.*;import java.util.concurrent.*;import java.util.stream.*;public class Car { private String model; private int year; public Car(String name, int year) { this.model = name; this.year = year; } public int getYear() {return year;} @Override public String toString() {return model;} public static void main(String... make) { List<Car> cars = new ArrayList<>(); cars.add(new Car("Mustang",1967)); cars.add(new Car("Thunderbird",1967));

cars.add(new Car("Escort",1975)); ConcurrentMap<Integer, List<Car>> map = cars .stream() .collect(Collectors.groupingByConcurrent(Car::getYear)); System.out.print(map); }}

A. {1975=[Escort], 1967=[Thunderbird, Mustang]}

B. {Escort=[1975], Thunderbird=[1967], Mustang=[1967]}


D. The application throws an exception at runtime because the stream is not parallel.


package exercise;import java.util.*;public class Concat { public String concat1(List<String> values) { return values.parallelStream() .reduce("a", (x,y)->x+y, String::concat); } public String concat2(List<String> values) { return values.parallelStream() .reduce((w,z)->z+w).get(); } public static void main(String... questions) { Concat c = new Concat(); List<String> list = Arrays.asList("Cat","Hat"); String x = c.concat1(list); String y = c.concat2(list); System.out.print(x+" "+y); }}

A. aCataHat HatCat

B. CatHat CatHat

C. The code does not compile because concat1() returns an Optional.



package taxes;import java.util.concurrent.*;public class Accountant { public static void completePaperwork() { System.out.print("[Filing]"); } public static double getPi() { return 3.14159;

} public static void main(String[] args) throws Exception { ExecutorService x = Executors.newSingleThreadExecutor(); Future<?> f1 = x.submit(() > completePaperwork()); Future<Object> f2 = x.submit(() > getPi()); System.out.print(f1.get()+" "+f2.get()); x.shutdown(); }}

A. [Filing]null 3.14159

B. The declaration of f1 does not compile.

C. The declaration of f2 does not compile.



package my;import java.util.*;public class ThreadSafeList { private List<Integer> data = new ArrayList<>(); public synchronized void addValue(int value) { data.add(value); } public int getValue(int index) { return data.get(index); } public int size() { synchronized(ThreadSafeList.class) { return data.size(); } }}

A. The code does not compile because of the size() method.

B. The code compiles and is thread-safe.

C. The code compiles and is not thread-safe.


29. Which two method names, when filled into the print2() method, produce the sameoutput as the print1() method? Assume the input arguments for each represent thesame non-null numeric value, only accessible by a single thread at a time.

public static void print1(int value) { System.out.println(value--); System.out.println(++value);}public static void print2(AtomicInteger value) { System.out.println(value.__________); System.out.println(value.__________);}

A. decrementAndGet() and getAndIncrement()

B. decrementAndGet() and incrementAndGet()

C. getAndDecrement() and getAndIncrement()

D. getAndDecrement() and incrementAndGet()

30. How many times does the following application print 1 at runtime?

package crew;import java.util.concurrent.*;import java.util.stream.*;public class Boat { private void waitTillFinished(CyclicBarrier c) { try { c.await(); System.out.print("1"); } catch (Exception e) {} } public void row(ExecutorService service) { final CyclicBarrier cb = new CyclicBarrier(5); IntStream.iterate(1, i-> i+1) .limit(12) .forEach(i -> service.submit(() > waitTillFinished(cb))); } public static void main(String[] oars) { ExecutorService service = null; try { service = Executors.newCachedThreadPool(); new Boat().row(service); } finally { service.isShutdown(); } }}

A. 0

B. 10

C. 12


31. Using the Boat class from the previous question, what is the final state of theapplication?

A. The application produces an exception at runtime.

B. The application terminates successfully.

C. The application hangs indefinitely because the ExecutorService is never shutdown.

D. The application produces a deadlock at runtime.

32. What is the expected output of the following application?

package store;import java.util.concurrent.*;import java.util.stream.*;public class Line { static BlockingDeque<Integer> queue = new LinkedBlockingDeque<>(); public static void main(String[] participants) throws Exception { IntStream.iterate(1, i -> i+1).limit(5) .parallel() .forEach(s -> queue.offerLast(s,10000,TimeUnit.MILLISECONDS)); IntStream.iterate(1, i -> 5).limit(10) .parallel() .forEach(s -> queue.pollFirst(10,TimeUnit.SECONDS)); System.out.print(queue.size()); }}

A. 0

B. A number from 0 to 5



33. Given the original array, how many of the following for statements result in aninfinite loop at runtime, assuming each is executed independently?

List<Integer> original = new ArrayList<>(Arrays.asList(1,2,3)); List<Integer> copy1 = new ArrayList<>(original);for(Integer q : copy1) copy1.add(1); List<Integer> copy2 = new CopyOnWriteArrayList<>(original);for(Integer q : copy2) copy2.add(2); Deque<Integer> copy3 = new ConcurrentLinkedDeque<>(original);for(Integer q : copy3) copy3.push(3);List<Integer> copy4 = Collections.synchronizedList(original);for(Integer q : copy4) copy4.add(4);

A. Zero

B. One

C. Two

D. Three

34. Three of the four following options make up the requirements for performing aparallel reduction with the collect() method, which takes a Collector argument.Choose the one that is not a requirement.

A. The Collector argument is marked concurrent.

B. The elements of the stream implement the Comparable interface.

C. The stream is parallel.

D. The stream or Collector is marked unordered.

35. Which statement about the following application is true?

package math;import java.util.concurrent.*;public class Fun extends RecursiveTask<Integer> { final int value; public Fun(int value) { this.value = value; } @Override protected Integer compute() { // w1 if(value<1) { return 1; } final Fun f1 = new Fun(value-1); final Fun f2 = new Fun(value-2); return f1.compute() * f2.compute(); } public static void main(String... data) { ForkJoinPool pool = new ForkJoinPool(); try { System.out.print(pool.invoke(new Fun(10))); } finally { pool.shutdown(); } }}

A. The class does not compile due to line w1.

B. The class does not compile for another reason.

C. The application compiles and uses the fork/join framework correctly.

D. The application compiles but does not use the fork/join framework correctly.

36. Which ExecutorService method guarantees all running tasks are stopped in an orderlyfashion?

A. shutdown()

B. shutdownNow()

C. halt()


37. Given the following code snippet, what statement about the values printed on lines p1and p2 is correct?

List<Integer> db = Collections.synchronizedList(new ArrayList<>());IntStream.iterate(1, i -> i+1).limit(5) .parallel()

.map(i -> {db.add(i); return i;}) .forEachOrdered(System.out::print); // p1System.out.println();db.forEach(System.out::print); // p2

A. They are always the same.

B. They are sometimes the same.

C. They are never the same.

D. The code will produce a ConcurrentModificationException at runtime.

38. Assuming 10 seconds is enough time for all of the tasks to finish, what is the output ofthe following application?

package finance;import java.util.concurrent.*;public class Bank { static int cookies = 0; public synchronized void deposit(int amount) { cookies += amount; } public static synchronized void withdrawal(int amount) { cookies -= amount; } public static void main(String[] amount) throws Exception { ExecutorService teller = Executors.newScheduledThreadPool(50); Bank bank = new Bank(); for(int i=0; i<25; i++) { teller.submit(() -> bank.deposit(5)); teller.submit(() -> bank.withdrawal(5)); } teller.shutdown(); teller.awaitTermination(10, TimeUnit.SECONDS); System.out.print(bank.cookies); }}

A. 0


C. The result is unknown until runtime.



package util;import java.util.*;public class SearchList<T> { private List<T> data; private boolean foundMatch = false; public SearchList(List<T> list) { this.data = list; } public void exists(T value,int start, int end) {

if(end-start<=1) { foundMatch = foundMatch || value.equals(data.get(start)); } else { final int middle = start + (end-start)/2; new Thread(() -> exists(value,start,middle)).run(); new Thread(() -> exists(value,middle,end)).run(); } } public static void main(String[] a) throws Exception { List<Integer> data = Arrays.asList(1,2,3,4,5,6); SearchList<Integer> t = new SearchList<Integer>(data); t.exists(5, 0, data.size()); System.out.print(t.foundMatch); }}

A. true

B. false


D. The result is unknown until runtime.

40. How many lines of the following code snippet contain compilation errors?

11: ScheduledExecutorService t = Executors12: .newSingleThreadScheduledExecutor();13: Future result = t.execute(System.out::println);14: t.invokeAll(null);15: t.scheduleAtFixedRate(() -> {return;}, 5, TimeUnit.MINUTES);


B. One

C. Two

D. Three

Chapter 21Building Database Applications with JDBCTHE OCP EXAM TOPICS COVERED IN THIS PRACTICE TEST INCLUDETHE FOLLOWING:

Building Database Applications with JDBC

Describe the interfaces that make up the core of the JDBC API including theDriver, Connection, Statement, and ResultSet interfaces and their relationship toprovider implementations

Identify the components required to connect to a database using theDriverManager class including the JDBC URL

Submit queries and read results from the database including creating statements,returning result sets, iterating through the results, and properly closing result sets,statements, and connections

1. How many of Connection, Driver, and DriverManager are JDBC interfaces includedwith the JDK?

A. None

B. One

C. Two

D. Three

2. Which is found in the java.sql package?

A. DerbyDriver

B. MySqlDriver

C. OracleDriver


3. What must be the first characters of a database URL?

A. db,

B. db:

C. jdbc,

D. jdbc:

4. Which is responsible for getting a connection to the database?

A. Driver

B. Connection

C. Statement

D. ResultSet

5. Which most accurately fills in the blanks in this sentence? With JDBC 3.0, the driveris__________ to contain a java.sql.Driver file, and the code getting a Connectionis __________ to call Class.forName().

A. allowed, allowed

B. allowed, required

C. required, allowed

D. required, required

6. Which of these obtains a Connection?

A. Connection.getConnection(url)

B. Driver.getConnection(url)

C. DriverManager.getConnection(url)

D. new Connection(url)

7. Which method is overloaded to allow passing a username and password?

A. forName()

B. getConnection()

C. getStatement()


8. What is the name of a concrete class that implements Statement and is included in thecore JDK?

A. CallableStatement

B. PreparedStatement

C. StatementImpl


9. How many of the following could be valid JDBC URL formats for an imaginary drivernamed magic and a database named box?

I. jdbc:magic:127.0.0.1:1234/box

II. jdbc:magic:box

III. jdbc:magic:@127.0.0.1:1234

A. None

B. One

C. Two

D. Three

10. Which most accurately fills in the blanks in this sentence? With JDBC 4.0, the driveris__________ to contain a java.sql.Driver file, and the code getting a Connectionis __________ to call Class.forName().

A. allowed, allowed

B. allowed, required

C. required, allowed

D. required, required

11. Which pair of statements is true when requesting a ResultSet to be both scrollsensitive and updatable?

I. The scroll sensitive option is passed as a parameter before the updatable

parameter.

II. The updatable option is passed as a parameter before the scroll sensitiveparameter.

III. If these options are not available, the database driver returns a ResultSet withdifferent options.

IV. If these options are not available, the database driver throws a SQLException.

A. I, III

B. I, IV

C. II, III

D. II, IV

12. Suppose the blue database exists and we are using a JDBC 4.0 driver. Which is theoutcome of this code?

String url = "jdbc:derby:blue";Class.forName(url);try (Connection conn = DriverManager.getConnection(url); Statement stmt = conn.createStatement(); ResultSet rs = stmt.executeQuery("select count(*) from sky")) { System.out.println(rs.getInt(1));}

A. It runs successfully and prints the number of rows in the sky table.

B. It throws a ClassNotFoundException.

C. It throws a SQLException.


13. Fill in the blanks: There are __________ ResultSet concurrency modes, and driversare required to support __________.

A. two, both

B. two, one of them

C. three, two of them

D. three, all of them

14. What is the output when run with a JDBC 4.0 driver if the clowns database exists andcontains an empty clowns table?

String url = "jdbc:derby:clowns";try (Connection conn = DriverManager.getConnection(url); Statement stmt = conn.createStatement(); ResultSet rs = stmt.executeQuery("select count(*) from clowns")) { System.out.println(rs.getInt(1));

}

A. 0

B. 1



15. Consider the three methods execute(), executeQuery(), and executeUpdate(). Fill inthe blanks: __________ of these methods is/are allowed to run a DELETE SQLstatement while __________ of these methods is/are allowed to run an UPDATE SQLstatement.

A. One, one

B. One, two

C. Two, one

D. Two, two

16. Assuming the clowns database exists and contains one empty table named clowns,what is the output of the following when run using a JDBC 4.0 driver?

import java.sql.*; public class EmptyTable { public static void main(String[] args) throws SQLException { // s1 String url = "jdbc:derby:clowns"; try (Connection conn = new Connection(url); // s2 Statement stmt = conn.createStatement(); ResultSet rs = stmt.executeQuery("select * from clowns")) { if (rs.next()) System.out.println(rs.getString(1)); } }}

A. The code terminates successfully without any output.

B. The code does not compile due to line s1.

C. The code does not compile due to line s2.


17. Which are valid ResultSet types?

I. TYPE_BACKWARD_ONLY

II. TYPE_FORWARD_ONLY

III. TYPE_REVERSE_ONLY

A. II

B. I and II

C. II and III


18. Given the table books in the figure and a ResultSet created by running the followingSQL statement, which option prints the value 379?

select * from cert where title = 'OCA'

A. System.out.println(rs.getInt(1));

B. System.out.println(rs.getInt(2));

C. System.out.println(rs.getInteger(1));

D. System.out.println(rs.getInteger(2));

19. Given the table books in the previous question and a ResultSet created by running thisSQL statement, which option prints OCP?

select title from cert where num_pages > 500

A. System.out.println(rs.getString());

B. System.out.println(rs.getString("0"));

C. System.out.println(rs.getString("1"));

D. System.out.println(rs.getString("title"));

20. Assume the database exists with all referenced table and column names. Which is atrue statement when a JDBC 4.0 driver is used?

String url = "jdbc:derby:precipitation";try (Connection conn = DriverManager.getConnection(url); Statement stmt = conn.createStatement( ResultSet.CONCUR_READ_ONLY, ResultSet.TYPE_SCROLL_INSENSITIVE); ResultSet rs = stmt.execute( "select total from precip where type = 'rain'")) { System.out.println(rs.getString("total"));}

A. There is a compiler error on the line of code that creates the Statement.

B. There is a compiler error on the line of code that creates the ResultSet.

C. This code compiles and runs without error.

D. This code throws a SQLException at runtime.

21. Which resources have their close() method called when this code runs?

public static void runQuery(Connection conn) throws SQLException{ try (Statement stmt = conn.createStatement()) { ResultSet rs = stmt.executeQuery("select * from clowns"); rs.next(); }}

A. No close() methods are called.

B. Only Statement

C. Only Statement and Connection

D. Only Statement and ResultSet

22. Which statement is true about the JDBC core classes?

A. Driver is an implementation of DriverManager.

B. A general Connection implementation is included in the JDK.

C. A Statement automatically starts in auto-commit mode.

D. A ResultSet automatically starts pointing to the first row of data.

23. Which of the following is required in a database driver implementation?

A. A file named jdbc.driver

B. A file named java.sql.Driver

C. At least one implementation of the Connection interface


24. Given that the people table has 10 rows, what is the result of the following when usinga driver that supports a scroll sensitive ResultSet?

try (Connection conn = DriverManager.getConnection(url); Statement stmt = conn.createStatement( ResultSet.TYPE_SCROLL_SENSITIVE, ResultSet.CONCUR_READ_ONLY); ResultSet rs = stmt.executeQuery("select count(*) from people")) { rs.next(); rs.absolute(0); // q1 System.out.print(rs.getInt(1)); // q2}

A. 10


C. Line q1 throws a SQLException.

D. Line q2 throws a SQLException.

25. Given a scrollable updatable ResultSet that contains the following, what does the codesnippet output?

rs = stmt.executeQuery("select * from pens");rs.afterLast();rs.previous();rs.updateInt(2, 10);rs.updateRow();rs = stmt.executeQuery("select * from pens where color = 'red'");while (rs.next()) System.out.println(rs.getInt(2));

A. 0

B. 10



26. Given a scrollable updatable ResultSet represented by the image in the previousquestion, what does the code snippet output?

rs = stmt.executeQuery("select * from pens");rs.afterLast();while(rs.prev()) rs.updateInt(2,0);rs = stmt.executeQuery("select * from pens where color = 'black'");while (rs.next()) System.out.println(rs.getInt(2));

A. 0

B. 20



27. How many rows are added to the colors table from running the following?

try (Connection conn = DriverManager.getConnection(url); Statement stmt = conn.createStatement()) { conn.setAutoCommit(false); stmt.executeUpdate("insert into colors values ('red')");

stmt.executeUpdate("insert into colors values ('blue')"); conn.commit(); conn.setAutoCommit(true); stmt.executeUpdate("insert into colors values ('green')");}

A. None

B. One

C. Two

D. Three

28. Which is true if the clowns database exists and contains an empty clowns table?

String url = "jdbc:derby:clowns";try (Connection conn = DriverManager.getConnection(url); Statement stmt = conn.createStatement(); ResultSet rs = stmt.executeQuery("select count(*) from clowns")) { rs.next(); // r1 System.out.println(rs.getInt(1)); // r2}

A. The code compiles and runs without error.


C. The code compiles but throws an exception at runtime on line r1.

D. The code compiles but throws an exception at runtime on line r2.

29. Suppose the ResultSet is scrollable and contains 10 rows with the values 1–10respectively. What is the output of the following?

5: rs.absolute(0);6: rs.relative(5);7: rs.relative(-10);8: rs.relative(5);9: System.out.print(rs.getInt(1));

A. 4

B. 5



30. Suppose the blue database does not exist and we are using a JDBC 4.0 driver. Which isthe outcome of this code?

String url = "jdbc:derby:blue";try (Connection conn = DriverManager.getConnection(url); Statement stmt = conn.createStatement(); ResultSet rs = stmt.executeQuery("select count(*) from sky")) { System.out.println(rs.getInt(1));

}

A. It runs successfully and prints the number of rows in the sky table.

B. It throws a ClassNotFoundException.

C. It throws a SQLException.


31. What is the most likely outcome of this code if the people table is empty?

6: Statement stmt = conn.createStatement();7: ResultSet rs1 = stmt.executeQuery("select * from people");8: ResultSet rs2 = stmt.executeQuery("select * from people");9: System.out.println(rs1.next() + " " + rs2.next());

A. It prints false false.

B. It prints true false.

C. It does not terminate.

D. It throws a SQLException.


try (Connection conn = DriverManager.getConnection(url); Statement stmt = conn.createStatement()) { conn.setAutoCommit(false); stmt.executeUpdate("insert into colors values ('red')"); stmt.executeUpdate("insert into colors values ('blue')"); conn.rollback(); conn.setAutoCommit(true); stmt.executeUpdate("insert into colors values ('green')");}

A. None

B. One

C. Two

D. Three

33. Assuming the clowns database exists and contains one empty table named clowns,what is the output of the following when run using a JDBC 4.0 driver?

import java.sql.*; public class EmptyTable { public static void main (String[] args) throws SQLException { // s1 String url = "jdbc:derby:clowns"; try (Connection conn = DriverManager.getConnection(url); // s2 Statement stmt = conn.createStatement(); ResultSet rs = stmt.executeQuery("select * from clowns")) {

if (rs.next()) System.out.println(rs.getString(1)); } }}

A. The code terminates successfully without any output.

B. The code does not compile due to line s1.

C. The code does not compile due to line s2.


34. Given the following code snippet and the table below, what is the output of thefollowing when using a driver that supports a scroll sensitive ResultSet?

try (Connection conn = DriverManager.getConnection(url); Statement stmt = conn.createStatement( ResultSet.TYPE_SCROLL_SENSITIVE, ResultSet.CONCUR_READ_ONLY); ResultSet rs = stmt.executeQuery( "select * from people order by last_name asc")) { rs.afterLast(); rs.next(); rs.next(); rs.previous(); rs.previous(); System.out.println(rs.getString(1));}

A. Janeice

B. Elena

C. Scott

D. The code throws a SQLException at runtime.

35. Given the following code snippet and the table in question 34, what is the output ofthe following when using a driver that supports a scroll sensitive ResultSet?

try (Connection conn = DriverManager.getConnection(url); Statement stmt = conn.createStatement( ResultSet.TYPE_SCROLL_SENSITIVE, ResultSet.CONCUR_READ_ONLY); ResultSet rs = stmt.executeQuery( "select * from people order by last_name asc")) {

rs.absolute(-1); System.out.print(rs.getString(1)); System.out.print(" "); rs.absolute(1); System.out.print(rs.getString(1));}

A. Jeanne Scott

B. Scott Jeanne

C. The code compiles, but the output is neither of these.


36. Given the following code snippet and the table in question 34, what is the output ofthe following?

try (Connection conn = DriverManager.getConnection(url); Statement stmt = conn.createStatement(); ResultSet rs = stmt.executeQuery( "select * from people order by last_name asc")) { rs.next(); rs.next(); System.out.print(rs.getString(1)); System.out.print(" "); rs.absolute(1); System.out.print(rs.getString(1));}

A. Jeanne Scott

B. Scott Jeanne

C. The code compiles, but the output is neither of these.


37. Given that the people table has 10 rows, what is the result of the following when usinga driver that supports a scroll sensitive Resultset?

String sql = "select count(*) from people";try (Connection conn = DriverManager.getConnection(url); Statement stmt = conn.createStatement(); ResultSet rs = stmt.executeQuery(sql, ResultSet.TYPE_SCROLL_SENSITIVE, ResultSet.CONCUR_READ_ONLY)) { rs.next(); rs.absolute(0); // q1 System.out.print(rs.getInt(1)); // q2}

A. 10


C. Line q1 throws a SQLException.

D. Line q2 throws a SQLException.


try (Connection conn = DriverManager.getConnection(url); Statement stmt = conn.createStatement()) { conn.setAutoCommit(false); stmt.executeUpdate("insert into colors values ('red')"); stmt.executeUpdate("insert into colors values ('blue')"); conn.rollback(); conn.setAutoCommit(true); stmt.executeUpdate("insert into colors values ('green')"); conn.rollback();}

A. None

B. One

C. Two

D. Three

39. Suppose the ResultSet is scrollable and contains 10 rows. How many times does thefollowing print true?

16: System.out.println(rs.absolute(-2));17: System.out.println(rs.relative(-1));18: System.out.println(rs.beforeFirst());19: System.out.println(rs.relative(5));

A. Two

B. Three

C. Four


40. What is the correct order to close database resources?

A. Connection then Statement then ResultSet

B. ResultSet then Statement then Connection

C. Statement then Connection then ResultSet

D. Statement then ResultSet then Connection

Chapter 22LocalizationTHE OCP EXAM TOPICS COVERED IN THIS PRACTICE TEST INCLUDE THEFOLLOWING:

Localization

Read and set the locale by using the Locale object

Create and read a Properties file

Build a resource bundle for each locale and load a resource bundle in anapplication

1. Which is not a locale?

A. Cultural region

B. Geographical region

C. Political region

D. Time zone region

2. When localizing an application, which type of data varies in presentation depending onlocale?

A. Currencies

B. Dates

C. Both

D. Neither

3. How do you find out the locale of the running program?

A. Locale.get("default")

B. Locale.get(Locale.DEFAULT)

C. Locale.getDefault()


4. If your application has all town names in a single file named strings.properties,what is the most specific process that has been implemented?

A. Internationalization

B. Localization

C. Specialization

D. Translation

5. Which interfaces does Properties implement?

I. Hashtable

II. HashMap

III. Map

A. III

B. I and II

C. I and III

D. II and III

6. Which filename extension can hold a String property value in a resource bundle?

A. .java

B. .properties



7. How long will the effects of calling Locale.setDefault() be active assuming no othercalls to that method are made?

A. Until the end of the method

B. Until the program exits

C. Until the next reboot of the computer

D. None of the above. It persists even past a reboot.

8. Given this properties file used to load the Properties object props and this codesnippet, what is the output?

mystery=bagtype=paper18: System.out.print(props.getProperty("mystery"));19: System.out.print(" ");20: System.out.print(props.getProperty("more"));

A. bag

B. bag null

C. bag ?

D. This code throws a runtime exception on line 20.

9. Fill in the blanks to complete the following code for a Java resource bundle.

public class Flights_en extends __________ { protected Object[][] __________() { return new Object[0][0]; }}

A. JavaResourceBundle, getContents

B. JavaResourceBundle, getProperties

C. ListResourceBundle, getContents

D. ListResourceBundle, getProperties

10. Which of the following shows a valid Locale format for the language Hindi and thecountry India?

A. hi_IN

B. HI_in

C. in_HI

D. IN_hi

11. If the key purple is in all four of these files, which file will the following code use forthe resource bundle?

Locale.setDefault(new Locale("en", "US"));ResourceBundle rb = ResourceBundle.getBundle("Colors");rb.getString("purple");

A. Colors.class

B. Colors.properties

C. Colors_en_US.class

D. Colors_en_US.properties


package counter;import java.util.*; public class CountResource extends ListResourceBundle { private int count = 0; @Override protected Object[][] getContents() { return new Object[][] { { "count", count++ } }; } public static void main(String[] args) { ResourceBundle rb = ResourceBundle.getBundle("counter.CountResource"); System.out.println(rb.getObject("count") + " " + rb.getObject("count")); }}

A. 0 0

B. 0 1



13. Which of the following shows a valid Locale format?

A. en

B. US

C. US_en


14. Which filename extension can define a LocalDateTime property value in a resourcebundle?

A. .java

B. .properties



15. What happens if you run this code with no resource bundles available?

ResourceBundle rb = ResourceBundle.getBundle("ghost.None");

A. It creates a resource bundle with no key/value pairs.

B. It runs without issue because the resource bundle is only searched for whengetting the first key.

C. It throws a MissingResourceException.



Map<String, String> map = new TreeMap<>();map.put("tool", "hammer");map.put("problem", "nail"); Properties props = new Properties(); // p1map.forEach((k,v) -> props.put(k, v)); // p2 String t = props.get("tool"); // p3String n = props.get("nail");System.out.println(t + " " + n);

A. hammer nail

B. The code does not compile due to line p1.

C. The code does not compile due to line p2.

D. The code does not compile due to line p3.

17. Which filename extension can hold a LocalDateTime property key in a resourcebundle?

A. .java

B. .properties



18. If the key purple is in all four of these files, which file will the following code use forthe resource bundle?

Locale.setDefault(new Locale("en", "US"));ResourceBundle rb = ResourceBundle.getBundle("Colors");rb.getString("purple");

A. Colors_en.class

B. Colors_en.properties

C. Colors_US.class

D. Colors_US.properties

19. Fill in the blank so the code correctly compiles and creates a Locale.

Locale loc = Locale.____________________;

A. get("Italian")

B. get(Locale.ITALIAN)

C. getLocale("Italian")



Map<Object, Object> map = new TreeMap<>();map.put("tool", "hammer");map.put("problem", "nail"); Properties props = new Properties(); // p1map.forEach((k,v) -> props.put(k, v)); // p2 String t = props.getProperty("tool"); // p3String n = props.getProperty("problem");System.out.println(t + " " + n);

A. hammer nail





1: package keyboard;2: import java.util.*;3:4: public class Type {5: protected Object[][] getContents() {6: return new Object[][] { { "keys", new ArrayList<String>() }};7: }8: public static void main(String[] args) {9: ResourceBundle rb = ResourceBundle.getBundle("keyboard.Type");10: List<String> keys = (List) rb.getObject("keys");11: keys.add("q");12: keys.add("w");

13: keys.add("e");14: keys.add("r");15: keys.add("t");16: keys.add("y");17: System.out.println(((List) rb.getObject("keys")).size());18: }19: }

A. 0

B. 6



22. How many lines does the following print out?

3: Locale.setDefault(Locale.KOREAN);4: System.out.println(Locale.getDefault());5: Locale.setDefault(new Locale("en", "AU"));6: System.out.println(Locale.getDefault());7: Locale.setDefault(new Locale("EN"));8: System.out.println(Locale.getDefault());

A. None; it does not compile.

B. One followed by an exception

C. Two followed by an exception

D. All three

23. Given this properties file used to load the Properties object props and this codesnippet, what is the output?

mystery=bagtype=paper 18: System.out.print(props.getProperty("mystery", "?"));19: System.out.print(" ");20: System.out.print(props.getProperty("more", "?"));

A. bag

B. bag null

C. bag ?

D. This code throws a runtime exception on line 20.

24. Given the following four properties files, what does this code print?

Locale.setDefault(new Locale("en", "US"));ResourceBundle rb = ResourceBundle.getBundle( "Cars", new Locale("fr", "FR"));System.out.println(rb.getString("country") + " " + rb.getString("engine"));

A. France engine

B. France moteur

C. France null


25. Given the four properties files in question 24, what does this code print?

Locale.setDefault(new Locale("en", "US"));ResourceBundle rb = ResourceBundle.getBundle( "Cars", new Locale("fr", "CA"));System.out.println(rb.getString("engine") + " " + rb.getString("horses"));

A. engine 241

B. moteur 241

C. moteur null


26. Given the four properties files in question 24, what does this code print?

Locale.setDefault(new Locale("fr", "CA"));ResourceBundle rb = ResourceBundle.getBundle( "Cars", new Locale("en", "CA"));System.out.println(rb.getString("engine") + " " + rb.getString("horses"));

A. engine 241

B. moteur 241

C. moteur null


27. Which statement about ListResourceBundle is true?

A. A disadvantage over properties files is that you cannot create the value at runtime.

B. Names-fr.java is a bad implementation class name.

C. Values of type Integer are not allowed.


28. If the key red is in all four of these files, which file will the following code use for theresource bundle?

Locale loc = new Locale("zh", "CN");Locale.setDefault(new Locale("en", "US"));ResourceBundle rb = ResourceBundle.getBundle("Colors", loc);rb.getString("red");

A. Colors_CN.properties

B. Colors_en.properties

C. Colors_US.properties

D. Colors_zh.properties


package counter;import java.util.*; public class PropertyCounter extends ListResourceBundle { private int count = 0; @Override protected Object[][] getContents() { return new Object[][] {{ "count", new PropertyCounter() }}; } public int getCount() { return count++; } public static void main(String[] args) { ResourceBundle rb = ResourceBundle.getBundle("counter.PropertyCounter"); PropertyCounter obj = (PropertyCounter) rb.getObject("count"); System.out.println(obj.getCount() + " " + obj.getCount()); }}

A. 0 0

B. 0 1




1: package keyboard;2: import java.util.*;3:4: public class Type extends ListResourceBundle {5: protected Object[][] getContents() {6: return new Object[][] { { "keys", new ArrayList<String>() }};7: }8: public static void main(String[] args) {9: ResourceBundle rb = ResourceBundle.getBundle("Type");10: List<String> keys = (List) rb.getObject("keys");11: keys.add("q");12: keys.add("w");13: keys.add("e");14: keys.add("r");15: keys.add("t");16: keys.add("y");17: System.out.println(((List) rb.getObject("keys")).size());18: }19: }

A. 0

B. 6



31. Given the following snippets of resource bundles from when we compiled theapplication, what is the result of the following?

Locale.setDefault(new Locale("en", "US"));ResourceBundle rb = ResourceBundle.getBundle("Buggy");System.out.println(rb.getString("wheels"));

A. null

B. 4

C. 6


32. Given the snippets of resource bundles in question 31 from when we compiled theapplication, what is the result of the following?

Locale.setDefault(new Locale("en"));ResourceBundle rb = ResourceBundle.getBundle("Buggy");System.out.println(rb.getString("color"));

A. null

B. black

C. white


33. Given the snippets of resource bundles in question 31 from when we compiled theapplication, what is the result of the following?

Locale.setDefault(new Locale("zh"));ResourceBundle rb = ResourceBundle.getBundle("Buggy");System.out.println(rb.getString("wheels"));

A. null

B. 4

C. 6


34. If the key red is in all three of these files, which file will the following code use for theresource bundle?


A. Colors_en.properties

B. Colors.properties

C. Red_en.properties

D. None of the above. It will throw a MissingResourceException.

35. Which can fill in the blank in this code?

Properties props = new Properties();props.__________("x");

A. get

B. getProperty




1: package keyboard;2: import java.util.*;3:4: public class Type extends ListResourceBundle {5: protected Object[][] getContents() {6: return new Object[][] { { "keys", new ArrayList<String>() }};7: }8: public static void main(String[] args) {9: ResourceBundle rb = ResourceBundle.getBundle("keyboard.Type");10: List<String> keys = (List) rb.getObject("keys");11: keys.add("q");12: keys.add("w");13: keys.add("e");14: keys.add("r");15: keys.add("t");16: keys.add("y");17: System.out.println(((List) rb.getObject("keys")).size());18: }19: }

A. 0

B. 6




Map<String, String> map = new TreeMap<>();map.put("tool", "hammer");map.put("problem", "nail"); Property props = new Property(); // p1map.forEach((k,v) -> props.put(k, v)); // p2 String t = props.getProperty("tool"); // p3String n = props.getProperty("nail");System.out.println(t + " " + n);

A. hammer nail





package counter;import java.util.*; public class CountResource extends ListResourceBundle { private int count = 0; @Override protected Object[][] getContents() { return new Object[][] { { "count", count++ } }; } public static void main(String[] args) { ResourceBundle rb = new ResourceBundle("counter.CountResource"); System.out.println(rb.getObject("count") + " " + rb.getObject("count")); }}

A. 0 0

B. 0 1



39. Given the following two properties files in the pod package, what does the followingclass output?

pod.container.propertiesname=genericnumber=2 pod.container_en.propertiesname=Dockertype=container package pod;import java.util.*;public class WhatKind { public static void main(String[] args) { Locale.setDefault(new Locale("en")); ResourceBundle rb = ResourceBundle.getBundle("pod.container"); String name = rb.getString("name"); String type = rb.getString("type"); System.out.println(name + " " + type); }}

A. Docker container

B. generic container

C. generic null


40. If the key red is in all three of these files, which file will the following code use for the

resource bundle?


A. Colors_EN.properties

B. Colors_ZH.properties

C. Red_EN.properties

D. None of the above. It will throw a MissingResourceException.

Chapter 23OCP Practice ExamThis chapter contains 85 questions and is designed to simulate a real OCP exam. Whileprevious chapters were focused on a specific set of objectives, this chapter covers all ofthe objectives on the exam. We recommend you take this exam only after you score wellon the questions in the individual chapters.

For this chapter, you should try to simulate the real exam experience as much as possible.This means setting aside 150 minutes of uninterrupted time to complete the test, as wellas not looking at any reference material while taking the exam. If you don’t know ananswer to a question, complete it as best you can and move on to the next question, justas you would on a real exam.

Remember, the exam permits writing material, such as a whiteboard. If you do not have awhiteboard handy, you can just use blank sheets of paper and a pencil. If you do well onthis test, then you are hopefully ready to take the real exam. With that said, good luck!

1. Suppose the ResultSet is scrollable and contains 10 rows with values numbered from1 to 10 in ascending order. What is true about the following? (Choose two.)

12: rs.beforeFirst();13: System.out.println(rs.relative(5));14: System.out.println(rs.getInt(1));15: System.out.println(rs.relative(-10));16: System.out.println(rs.getInt(1));17: System.out.println(rs.relative(5));18: System.out.print(rs.getInt(1));

A. It outputs true once.

B. It outputs true twice.

C. It outputs true three times.

D. It completes without throwing an exception.

E. It throws an exception at runtime.


public class PiDay { public static void main(String[] args) { LocalDateTime pi = LocalDateTime.of(2017, 3, 14, 1, 59); DateTimeFormatter formatter = DateTimeFormatter .ofPattern("m.ddhhMM"); System.out.println(formatter.format(pi)); }}

A. 3.011459

B. 3.140159

C. 59.011459

D. 59.140103



3. Which of the following are valid lambda expressions? (Choose three.)

A. () -> {}

B. (Double adder) -> {int y; System.out.print(adder); return adder;}

C. (Long w) -> {Long w=5; return 5;}

D. (int count, vote) -> count*vote

E. dog -> dog

F. name -> {name.toUpperCase()}


package names;import java.util.*;import java.util.function.*;interface ApplyFilter { void filter(List<String> input);}public class FilterBobs { static Function<String,String> first = s > {System.out.println(s); return s;}; static Predicate second = t -> "bob".equalsIgnoreCase(t); public void process(ApplyFilter a, List<String> list) { a.filter(list); } public static void main(String[] contestants) { final List<String> people = new ArrayList<>(); people.add("Bob"); people.add("bob"); people.add("Jennifer"); people.add("Samantha"); final FilterBobs f = new FilterBobs(); f.process(q -> { q.removeIf(second); q.forEach(first); }, people); }}

A. It prints two lines.

B. It prints three lines.

C. One line of code does not compile.


E. Three lines of code do not compile.

F. The code compiles but prints an exception at runtime.


public class Compete { public static void main(String[] args) { Stream<Integer> is = Stream.of(8, 6, 9); Comparator<Integer> c = (a, b) > b a; // r1 is.sorted(c).forEach(System.out::print); // r2 }}

A. 689

B. 986


D. The code does not compile because of line r2.

E. The code does not compile due to another line.



package tax; public class Accountant { class AddingException extends Exception {}; class DividingException extends Exception {}; class UnexpectedException extends RuntimeException {}; public void doTaxes() throws Throwable { try { throw new IllegalStateException(); } catch (AddingException | DividingException e) { // p1 System.out.println("Math Problem"); } catch (UnexpectedException | Exception f) { // p2 System.out.println("Unknown Error"); throw f; } } public static void main(String[] numbers) throws Throwable { try { new Accountant().doTaxes(); } finally { System.out.println("All done!"); } }}

A. Math Problem

B. Unknown Problem

C. Unknown Problem followed by All done!

D. The code does not compile solely due to line p1.

E. The code does not compile solely due to line p2.

F. The code does not compile due to lines p1 and p2.


1: package drawing;2: interface HasHue {String getHue();}3: enum COLORS implements HasHue {4: red {5: public String getHue() {return "FF0000";}6: }, green {7: public String getHue() {return "00FF00";}8: }, blue {9: public String getHue() {return "0000FF";}10: }11: }12: class Book {13: static void main(String[] pencils) {}14: }15: final public class ColoringBook extends Book {

16: final void paint(COLORS c) {17: System.out.print("Painting: "+c.getHue());18: }19: final public static void main(String[] crayons) {20: new ColoringBook().paint(COLORS.green);21: }22: }

A. Painting: 00FF00

B. One line of code does not compile.

C. Two lines of code do not compile.

D. Three lines of code do not compile.

E. The code compiles but prints an exception at runtime.


8. How many of the following can fill in the blank to make this code compile?

public boolean isItMyBirthday(LocalDateTime dateTime) { ________________________________________ return now.getMonth() == dateTime.getMonth() && now.getDayOfMonth() == dateTime.getDayOfMonth();}

I. LocalDate now = LocalDate.now();

II. LocalDate now = new LocalDate();

III. LocalDateTime now = LocalDateTime.now();

IV. LocalDateTime now = new LocalDateTime();

V. ZonedDate now = ZonedDate.now();

VI. ZonedDate now = new ZonedDate();

A. None

B. One

C. Two

D. Three

E. Four

F. Five

9. Which two can independently fill in the blank to output No dessert today? (Choosetwo.)

import java.util.*;public class Dessert {

public static void main(String[] yum) { eatDessert(Optional.empty()); } private static void eatDessert(Optional<String> opt) { System.out.println(opt.__________); }}

A. get("No dessert today")

B. get(() -> "No dessert today")

C. orElse("No dessert today")

D. orElse(() -> "No dessert today")

E. orElseGet("No dessert today")

F. orElseGet(() -> "No dessert today")


public class InitOrder { { System.out.print("1"); } static { System.out.print("2"); } public InitOrder() { System.out.print("3"); } public static void callMe() { System.out.print("4"); } public static void main(String[] args) { callMe(); callMe(); System.out.print("5"); }}

A. 1223445

B. 2445

C. 22445

D. 223445

E. 2233445


11. Which of the following cannot be instantiated directly by the caller using theconstructor?

I. Locale

II. Properties

III. ResourceBundle

A. I

B. II

C. III

D. I, II

E. I, III

F. II, III

12. What design pattern or principle is used in this class?

public class Daffodil { int height; public Daffodil(int height) { this.height = height; } public int getHeight() { return height; }}

A. Encapsulation

B. Immutability

C. Singleton

D. Both A and B

E. None of the above

13. What is the output of the following application? Assume the file system is availableand able to be written to and read from.

package boat;import java.io.*;public class Cruise { private int numPassengers = 1; private transient String schedule = "NONE"; {numPassengers = 2;} public Cruise() { this.numPassengers = 3; this.schedule = "Tropical Island"; } public static void main(String... passengers) throws Exception { try (ObjectOutputStream o = new ObjectOutputStream( new FileOutputStream("ship.txt"))) { Cruise c = new Cruise(); c.numPassengers = 4; c.schedule = "Casino"; o.writeObject(c); } try (ObjectInputStream i = new ObjectInputStream(

new FileInputStream("ship.txt"))) { Cruise c = i.readObject(); System.out.print(c.numPassengers+","+c.schedule); } }}

A. 2,NONE

B. 3,null

C. 4,Casino

D. 4,null

E. The class does not compile.

F. The class compiles but throws an exception at runtime.

14. Which of the following are JDBC interfaces in the java.sql package?

I. Driver

II. DriverManager

III. Query

IV. ResultSet

A. I, III

B. I, IV

C. II, III

D. II, IV

E. I, II, III

F. I, II, IV

15. Which of the following lambda expressions can be passed to a method that takesIntUnaryOperator as an argument? (Choose three.)

A. v -> {System.out.print("Hello!"); return 2%1;}

B. (Integer w) -> w.intValue()

C. (int j) -> (int)30L

D. (int q) -> q/3.1

E. (long x) -> (int)x

F. z -> z

16. Which of the following statements about InputStream and Reader are correct? (Choose

two.)

A. One contains a read() method that returns a byte value, while the other contains aread() method that returns an int value.

B. Only one of them contains a flush() method.

C. Only one of them contains a skip() method.

D. They are both abstract classes.

E. They are both interfaces.

F. They can both be used to read character data.

17. Fill in the blank so this code prints -1.

LocalDate xmas = LocalDate.of(2017, 12, 25);LocalDate blackFriday = LocalDate.of(2017, 11, 24);long monthsLeft = ChronoUnit.MONTHS.____________________;System.out.println(monthsLeft);

A. between(blackFriday, xmas)

B. between(xmas, blackFriday)

C. minus(blackFriday, xmas)

D. minus(xmas, blackFriday)

E. plus(blackFriday, xmas)

F. plus(xmas, blackFriday)

18. Which statements about the following class are true?

package secure;import java.io.*;public class Login { public void clearPassword(char[] password) { for(int i=0; i<password.length; i++) { password[i] = 0; } } public String getPassword() { Console c = System.console(); final char[] pass = c.readPassword("Enter your password: "); StringBuilder sb = new StringBuilder(); for(char p : pass) { sb.append(p); } clearPassword(pass); return sb.toString(); } public static void main(String[] webLogin) { String pass = new Login().getPassword(); }}

I. The class compiles.

II. The design protects the password by clearing it from memory after it is entered.

III. The class may throw an exception at runtime.

A. I only

B. II only

C. I and II only

D. I and III only

E. I, II, and III

19. Which of the following can fill in the blank to print out the numbers 161, 183, and 201in any order?

class Runner { private int numberMinutes; public Runner(int n) { numberMinutes = n; } public int getNumberMinutes() { return numberMinutes; }}public class Marathon { public static void main(String[] args) { Stream<Runner> runners = Stream.of(new Runner(183), new Runner(161), new Runner(201)); OptionalInt opt = runners.____________________; }}

A. map(Runner::getNumberMinutes)

.peek(System.out::println).max()

B. mapToInt(Runner::getNumberMinutes)

.peek(System.out::println).max()

C. peek(System.out::println)

.mapToInt(Runner::getNumberMinutes).max()

D. peek(System.out::println)

.mapToInt(Runner::getNumberMinutes).max()



1: package fruit;

2: enum Season {3: SPRING(1), SUMMER(2), FALL(3), WINTER(4)4: public Season(int orderId) {}5: }6: public class PickApples {7: public static void main(String... orchard) {8: final Season s = Season.FALL;9: switch(s) {10: case 3:11: System.out.println("Time to pick!");12: default:13: System.out.println("Not yet!");14: }15: }16: }

A. Time to pick!

B. Time to pick! followed by Not yet!

C. One line of code does not compile.


E. Three lines of code do not compile.

F. The code compiles but prints an exception at runtime.

21. Which of the following expressions, inserted simultaneously into both blanks, allowthe application to compile? (Choose three.)

package spooky;import java.util.function.*;abstract class Phantom { public void bustLater(DoubleConsumer buster, double value) { buster.accept(value); }}public class Ghost extends Phantom { public void bustNow(Consumer<Double> buster, double value) { buster.accept(value); } void call() { double value = 10; bustNow(__________,value); bustLater(__________,value); }}

A. System.out::print

B. a -> {System.out.println(a.intValue());}

C. g -> {System.out.println();}

D. u -> System.out.println((long)u)

E. v -> System.out.print(v)

F. w -> System.out::println


package counter;import java.util.*; public class CountResource extends ListResourceBundle { private int count = 0; @Override protected Object[][] getContents() { return new Object[][] { { "count", ++count } }; } public static void main(String[] args) { ResourceBundle rb = ResourceBundle.getBundle("counter.CountResource"); System.out.println(rb.getString("count") + " " + rb.getString("count")); }}

A. 0 0

B. 0 1

C. 1 1

D. 1 2



23. In most of the United States, daylight savings time ends on November 5, 2017 at 02:00a.m., and we repeat that hour. What is the output of the following?

import java.time.*; public class FallBack { public static void main(String[] args) { LocalDate localDate = LocalDate.of(2017, 10, 5); LocalTime localTime = LocalTime.of(1, 0); ZoneId zone = ZoneId.of("America/New_York"); ZonedDateTime z = ZonedDateTime.of(localDate, localTime, zone); for (int i = 0; i < 6; i++) z = z.plusHours(1); System.out.println(z.getHour()); }}

A. 5

B. 6

C. 7


E. The code compiles, but throws an exception at runtime.

24. Assume the /environment directory exists and contains a file with a symbolic link tothe /environment directory. In addition, assume all files within the directory are fullyaccessible. What is the result of executing the following program?

import java.nio.file.*;import java.nio.file.attribute.*;public class SearchEnvironment { public static void accessFile(Path p, long timeEpoch) { try { Files.readAttributes(p, BasicFileAttributes.class) .setTimes(null, null, FileTime.fromMillis(timeEpoch)); } catch (Throwable e) { } finally {} } public static final void main(String[] unused) throws Exception { Path w = Paths.get("/environment"); Files.walk(w) .forEach(q -> accessFile(q,System.currentTimeMillis())); }}


B. The program exits after successfully updating the creation time of files within thedirectory.

C. The program exits after successfully updating the last accessed time of files withinthe directory.

D. The program compiles but throws an exception at runtime.

E. The program enters an infinite loop and hangs at runtime.

25. Which command causes the following class to throw an AssertionError at runtime?

public class Watch { private static final short DEFAULT_HOUR = 12; private Watch() { super(); } int checkHour() { assert DEFAULT_HOUR > 12; return DEFAULT_HOUR; } public static void main(String... ticks) { new Watch().checkHour(); }}

A. java -da Watch

B. java -ea:Watch -da Watch

C. java -ea -da:Watch Watch

D. java -enableassert Watch

E. None of the above since the Watch class does not compile.


package rope;import java.util.concurrent.*;import java.util.stream.IntStream;public class Jump { private static void await(CyclicBarrier b) { try { b.await(); } catch (InterruptedException | BrokenBarrierException e) { e.printStackTrace(); } } public static void main(String[] chalk) { ExecutorService s = Executors.newFixedThreadPool(4); final CyclicBarrier b = new CyclicBarrier(4, () -> System.out.print("Jump!")); IntStream .iterate(1, q -> 2) .limit(10) .forEach(q -> s.execute(() >await(b))); s.shutdown(); }}

A. Jump! is printed and exits.

B. Jump! is printed twice and exits.


D. The output cannot be determined ahead of time.

E. The program hangs indefinitely at runtime because the IntStream is not parallel.


27. What is the output of the following code snippet? Assume the two directoriesreferenced both exist and are symbolic links to the same location within the filesystem.

if(Files.isSameFile("/salad/carrot", "/fruit/apple")) System.out.println("Same!");else System.out.println("Different!");

A. Same!

B. Different!




28. Which can fill in the blank JavaProgrammerCert class to compile and logically completethe code? (Choose two.)

class JavaProgrammerCert extends Exam { private Exam oca; private Exam ocp; // assume getters and setters are here ______________________________________ }public class Exam { boolean pass; protected boolean passed() { return pass; }}

A. boolean passed() { return oca.pass && ocp.pass; }

B. boolean passed() { return oca.passed() && ocp.passed(); }

C. boolean passed() { return super.passed(); }

D. public boolean passed() { return oca.passed() && ocp.passed(); }

E. public boolean passed() { return oca.pass && ocp.pass; }

F. public boolean passed() { return super.passed(); }

29. Which statements about overriding a method are correct? (Choose two.)

A. An overridden method must not throw a narrower version of any checkedexception thrown by the inherited method.

B. An overridden method must use a return type that is covariant with the inheritedmethod.

C. An overridden method must use a different set of input arguments as the inheritedmethod.

D. Overridden methods must use an access modifier at least as broad as theirinherited method.

E. It is possible to override private and static methods.

F. The @Override annotation is required anytime a method is overridden.

30. Which of the following can be independently inserted into the blank so the code canrun without error for at least one SQL query?

private static void choices(Connection conn, String sql) throws SQLException { try (Statement stmt = conn.createStatement(); ResultSet rs = stmt.executeQuery(sql)) { ____________________

}}

I. System.out.println(rs.getInt(1));

II. rs.next(); System.out.println(rs.getInt(1));

III. if (rs.next()) System.out.println(rs.getInt(1));

A. II

B. III

C. I and III

D. II and III

E. I, II, and III


31. Starting with DoubleBinaryOperator and going downward, fill in the values for thetable.

Functional Interface # ParametersDoubleBinaryOperator

LongToIntFunction

ToLongBiFunction

IntSupplier

ObjLongConsumer

A. 1, 0, 0, 0, 2

B. 1, 2, 1, 0, 1

C. 2, 1, 0, 1, 2

D. 2, 1, 1, 0, 1

E. 2, 1, 2, 0, 2

F. 3, 0, 2, 1, 1


LocalDate trainDay = LocalDate.of(2017, 5, 13);LocalTime time = LocalTime.of(10, 0);ZoneId zone = ZoneId.of("America/Los_Angeles");ZonedDateTime zdt = ZonedDateTime.of(trainDay, time, zone);Instant instant = zdt.toInstant();instant = instant.plus(1, ChronoUnit.YEARS);System.out.println(instant);


B. 2017-05-13T17:00:00Z

C. 2018-05-13T10:00-07:00[America/Los_Angeles]

D. 2018-05-13T17:00:00Z



33. How many lines does the following output?

import java.util.stream.*; class Blankie { String color; boolean isPink() { return "pink".equals(color); }}public class PreSchool { public static void main(String[] args) { Blankie b1 = new Blankie(); Blankie b2 = new Blankie(); b1.color = "pink"; Stream.of(b1, b2).filter(Blankie::isPink).forEach(System.out::println); }}

A. None

B. One

C. Two



34. Which are the minimum changes needed to make this class immutable?

1: public class Tree {2: String species;3: public Tree(String species) {4: this.species = species;5: }6: public String getSpecies() {7: return species;8: }9: private final void setSpecies(String newSpecies) {10: species = newSpecies;11: }12: }

I. Make species private and final.

II. Make the getter method final.

III. Remove the setter method.

A. None. It is already immutable.

B. I

C. I and II

D. I and III

E. II and III

F. I, II, and III

35. Let’s say you needed to write a large List of Student objects to a data file. Which threeconcrete classes, chained together, would best accomplish this? (Choose three.)

A. BufferedFileOutputStream

B. BufferedOutputStream

C. FileOutputStream

D. FileWriter

E. ObjectOutputStream

F. OutputStream

36. Which statements when inserted independently will throw an exception at runtime?(Choose two.)

ArrayDeque<Integer> d = new ArrayDeque<>();d.offer(18);// INSERT CODE HERE

A. d.peek(); d.peek();

B. d.poll(); d.poll();

C. d.pop(); d.pop();

D. d.remove(); d.remove();


11: Path x = Paths.get(".","song","..","/note");12: Path y = Paths.get("/dance/move.txt");13: x.normalize();14: System.out.println(x.resolve(y));15: System.out.println(y.relativize(x));

A. /./song/../note/dance/move.txt

/dance/move.txt

B. /dance/move.txt

/dance/move.txt/./song/../note

C. /dance/move.txt

/dance/move.txt/note

D. /note/dance/move.txt

../dance/move.txt/song


F. The code compiles but an exception is thrown at runtime.


package field;import java.io.*;class StungException extends Exception {}class Suit implements Closeable { public void close() throws IOException {}}public class BeeCatcher { public static void main(String... bees) { try (Suit s = new Suit(), Suit t = new Suit()) { throw new StungException(); } catch (Exception e) { } catch (StungException e) { } finally { } }}

A. One

B. Two

C. Three

D. Four

E. None. The code compiles as is.


package homework;import java.util.*;import java.util.stream.*;public class QuickSolution { public static int findFast(Stream<Integer> s) { return s.findAny().get(); } public static int findSlow(Stream<Integer> s) { return s.parallel().findFirst().get(); } public static void main(String[] pencil) { Stream<Integer> s1 = Arrays.asList(1,2,3,4,5).stream(); Stream<Integer> s2 = Arrays.asList(1,2,3,4,5).stream(); int val1 = findFast(s1);

int val2 = findSlow(s2); System.out.print(val1+" "+val2); }}

A. 1 1

B. 3 1

C. The answer cannot be determined until runtime.



40. Given this property file used to load the Properties object props and this code snippet,what is the output?

mystery=bagtype=paper 18: System.out.print(props.getDefaultProperty("mystery", "?"));19: System.out.print(" ");20: System.out.print(props.getDefaultProperty("more", "?"));

A. bag

B. bag null

C. bag ?



41. Which statements about try-with-resources are true? (Choose two.)

A. Any resource used must implement Closeable.

B. If more than one resource is used, then the order in which they are closed is thereverse of the order in which they were created.

C. If the try block and close() method both throw an exception, the one thrown bythe try block is suppressed.

D. Neither a catch nor a finally block is required.

E. The close() method of the resources must throw a checked exception.

42. How many lines fail to compile?

class Roller<E extends Wheel> { public void roll(E e) { }}class Wheel { }class CartWheel extends Wheel { } public class RollingContest {

Roller<CartWheel> wheel1 = new Roller<CartWheel>(); Roller<Wheel> wheel2 = new Roller<CartWheel>(); Roller<? extends Wheel> wheel3 = new Roller<CartWheel>(); Roller<? extends Wheel> wheel4 = new Roller<Wheel>(); Roller<? super Wheel> wheel5 = new Roller<CartWheel>(); Roller<? super Wheel> wheel6 = new Roller<Wheel>();}

A. One

B. Two

C. Three

D. Four

E. Five

F. Six

43. Which are the minimum changes needed to properly implement the singletonpattern?

1: public class Bookmark {2: private static Bookmark bookmark;3: private int pageNumber;4: static {5: bookmark = new Bookmark();6: }7: public static Bookmark getInstance() {8: return bookmark;9: }10: public int getPageNumber() {11: return pageNumber;12: }13: public void setPageNumber(int newNumber) {14: pageNumber = newNumber;15: }16: }

I. Add a private constructor.

II. Remove the setter method.

III. Remove the static block and change line 2 to instantiate Bookmark.

A. None. It is already a singleton.

B. I

C. I and II

D. I and III

E. II and III

F. I, II, and III

44. Given an updatable ResultSet that contains the following and this code, what does thecode snippet output?

rs.afterLast();rs.previous();rs.updateInt(2, 10); rs = stmt.executeQuery("select * from pens where color = 'red'");while (rs.next()) { System.out.println(rs.getInt(2));}

A. 0

B. 10



45. Which statements describe a java.io stream class and cannot be applied to ajava.util.stream.Stream class? (Choose three.)

A. Can be used with try-with-resources statement

B. Includes a class or set of classes used solely for working with character data

C. Requires all data objects to implement Serializable

D. Some classes contain a flush() method.

E. Some classes contain a method to skip over data.

F. Some classes contain a method to sort the data.

46. Bill wants to create a program that reads all of the lines of all of his books usingNIO.2. Unfortunately, Bill may have made a few mistakes writing his program. Howmany lines of the following class contain compilation errors?

1: package bookworm;2: import java.io.*;3: import java.nio.file.*;4: public class ReadEverything {5: public void readFile(Path p) {6: try {7: Files.readAllLines(p)8: .parallel()9: .forEach(System.out::println);

10: } catch (Exception e) {}11: }12: public void read(Path directory) throws Exception {13: Files.walk(directory)14: .filter(p -> File.isRegularFile(p))15: .forEach(x -> readFile(x));16: }17: public static void main(String... books) throws IOException {18: Path p = Path.get("collection");19: new ReadEverything().read(p);20: }21: }

A. None. Bill’s implementation is correct.

B. One

C. Two

D. Three

E. Four

F. Five

47. Assuming the following class is concurrently accessed by numerous threads, whichstatement about the CountSheep class is correct?

package fence;import java.util.concurrent.atomic.*;public class CountSheep { private static AtomicInteger counter = new AtomicInteger(); private Object lock = new Object(); public synchronized int increment1() { return counter.incrementAndGet(); } public static synchronized int increment2() { return counter.getAndIncrement(); } public int increment3() { synchronized(lock) { return counter.getAndIncrement(); } }}

A. The class is thread-safe only if increment1() is removed.

B. The class is thread-safe only if increment2() is removed.

C. The class is thread-safe only if increment3() is removed.

D. The class is already thread-safe.


F. The class compiles but may throw an exception at runtime.

48. Which of the following are not required parameters for the NIO.2 Files.find()method? (Choose two.)

A. BiPredicate

B. FileVisitOption...

C. int

D. long

E. Path

49. Which statements are correct? (Choose two.)

A. A Comparable implementation is often implemented by a lambda.

B. A Comparable object has a compare() method.

C. The compare() and compareTo() methods have the same contract for the returnvalue.

D. There can be multiple Comparator implementations for the same class.

E. Two objects that return true for equals() will always return 0 when passed tocompareTo().

50. What is the output of the following code snippet, assuming none of the filesreferenced exist within the file system?

Path t1 = Paths.get("/sky/.././stars.exe");Path t2 = Paths.get("/stars.exe");Path t3 = t1.resolve(t2); boolean b1 = t1.equals(t2);boolean b2 = t1.normalize().equals(t2);boolean b3 = Files.isSameFile(t1.normalize(),t2);boolean b4 = Files.isSameFile(t2,t3); System.out.print(b1+","+b2+","+b3+","+b4);

A. false,false,true,true

B. false,true,true,false

C. false,true,true,true

D. true,false,true,false



51. Let’s say we have a Reader instance that will produce the characters with the numericvalues {1,2,3,4,5,6,7}. Which of the following are possible outcomes of executingthe checkLottoNumbers() method with this Reader instance? (Choose two.)

23: public String checkLottoNumbers(Reader r) throws IOException {24: r.read();r.skip(1);25: r.mark(5);26: r.skip(1);27: r.reset();28: return r.read()+"-"+r.read(new char[5]);29: }

A. An IOException on line 25

B. An IOException on line 27

C. 'c'-4 is returned.

D. 'd'-3 is returned.

E. 3-4 is returned.

F. 4-3 is returned.

52. Fill in the blanks: The name of the abstract method in the Function interface__________ is , while the name of the abstract method in the Consumer interfaceis__________ .

A. accept(), apply()

B. accept(), get()

C. apply(), accept()

D. apply(), apply()

E. apply(), test()

53. Assuming the following program is executed with assertions enabled, which is the firstline to throw an exception at runtime?

1: package school;2: public class Teacher {3: public int checkClasswork(int choices) {4: assert choices++==10 : 1;5: assert true!=false : new StringBuilder("Answer2");6: assert(null==null) : new Object();7: assert ++choices==11 : "Answer4";8: assert 2==3 : "";9: return choices;10: }11: public final static void main(String... students) {12: try {13: new Teacher().checkClasswork(10);14: } catch (Error e) {15: System.out.print("Bad idea");16: throw e;17: }18: }19: }

A. Line 4

B. Line 5

C. Line 6

D. Line 7

E. Line 8

F. None of the above since the class does not compile

54. Which of the following are valid functional interfaces in the java.util.functionpackage? (Choose three.)

A. BooleanSupplier

B. CharSupplier

C. DoubleUnaryOperator

D. ObjectIntConsumer

E. ToLongBiFunction

F. TriPredicate

55. Which statements about the following class are correct? (Choose two.)

package knowledge;class InformationException extends Exception {}public class LackOfInformationException extends InformationException { public LackOfInformationException() { // t1 super(""); } public LackOfInformationException(String s) { // t2 this(new Exception(s)); } public LackOfInformationException(Exception c) { // t3 super(); } @Override public String getMessage() { return "lackOf"; }}

A. LackOfInformationException compiles without issue.

B. The constructor declared at line t1 does not compile.

C. The constructor declared at line t2 does not compile.

D. The constructor declared at line t3 does not compile.

E. The getMessage()method does not compile because of the @Override annotation.

F. LackOfInformationException is a checked exception.

56. How many changes do you need to make in order for this code to compile?

public class Ready {

private static double getNumber() { return .007; } public static void math() { Supplier<double> s = Ready:getNumber; double d = s.get(); System.out.println(d); }}

A. None

B. One

C. Two

D. Three

E. Four


package robot;import java.util.concurrent.*;public class PassButter extends RecursiveTask<String> { // j1 final int remainder; public PassButter(int remainder) { // j2 this.remainder = remainder; } @Override protected String compute() { if (remainder <= 1) return "1"; else { PassButter otherTask = new PassButter(remainder - 1); String otherValue = otherTask.fork().join(); // j3 return otherValue + new PassButter(remainder - 2).compute(); } } public static void main(String[] purpose) { ForkJoinPool pool = new ForkJoinPool(); ForkJoinTask<?> task = new PassButter(10); System.out.print(pool.invoke(task)); pool.shutdown(); }}

A. The code does not compile due to line j1.

B. The code does not compile due to line j2.

C. The code does not compile due to line j3.

D. The code compiles and properly implements the fork/join framework in a multi-threaded manner.

E. The code compiles but does not implement the fork/join framework in a proper

multi-threaded manner.

F. The class compiles and prints an exception at runtime.

58. Which can fill in the blank so this code outputs true?

import java.util.function.*;import java.util.stream.*; public class HideAndSeek { public static void main(String[] args) { Stream<Boolean> hide = Stream.of(true, false, true); Predicate<Boolean> pred = b > b; boolean found = hide.filter(pred).__________(pred); System.out.println(found); }}

A. Only anyMatch()

B. Only allMatch()

C. Both anyMatch() and allMatch()

D. Only noneMatch()

E. The code does not compile with any of these options.

59. Given the following code, Java will try to find a matching resource bundle. Whichorder will Java search to find a match?

Locale.setDefault(new Locale("en"));ResourceBundle.getBundle("AB", new Locale("fr"));

A. AB.class, AB.properties, AB_en.properties, AB_fr.properties

B. AB.properties, AB.class, AB_en.properties, AB_fr.properties

C. AB_en.properties, AB_fr.properties, AB.class, AB.properties

D. AB_fr.properties, AB.class, AB.properties, AB_en.properties

E. AB_fr.properties, AB_en.properties, AB.class, AB.properties

F. AB_fr.properties, AB_en.properties, AB.properties, AB.class


Set<Integer> dice = new TreeSet<>();dice.add(6);dice.add(6);dice.add(4);dice.stream().filter(n -> n != 4).forEach(System.out::println).count();

A. It prints just one line.

B. It prints one line and then the number 3.

C. There is no output.



61. Given the following two property files in the pod package, what does the followingclass output?

pod.container.propertiesname=genericnumber=2pod.container_en.propertiesname=Dockertype=containerpackage pod;import java.util.*;public class WhatKind { public static void main(String[] args) { Locale.setDefault(new Locale("ja")); ResourceBundle rb = ResourceBundle.getBundle("pod.container"); String name = rb.getString("name"); // r1 String type = rb.getString("type"); // r2 System.out.println(name + " " + type); }}

A. Docker container

B. generic container

C. generic null


E. Line r1 throws an exception.

F. Line r2 throws an exception.


import java.util.stream.*;public class StreamOfStreams { public static void main(String[] args) { Integer result = Stream.of(getNums(9, 8), getNums(22, 33)) // c1 .filter(x -> !x.isEmpty()) // c2 .flatMap(x -> x) // c3 .max((a, b) -> a b) // c4 .get(); System.out.println(result); } private static Stream<Integer> getNums(int num1, int num2) { return Stream.of(num1, num2); }}

A. The code compiles and outputs 8.

B. The code compiles and outputs 33.

C. The code does not compile due to line c1.

D. The code does not compile due to line c2.

E. The code does not compile due to line c3.

F. The code does not compile due to line c4.

63. Which of the following shows a valid Locale format? (Choose two.)

A. de

B. DE

C. de_DE

D. DE_de

64. What is true of the following if the music database exists and contains a songs tablewith one row when run using a JDBC 4.0 driver? (Choose two.)

import java.sql.*;public class Music { public static void main(String[] args) throws Exception { String url = "jdbc:derby:music"; Connection conn = DriverManager.getConnection(url); Statement stmt = conn.createStatement(); stmt.execute("update songs set name = 'The New Song'"); }}


B. The code does not update the database because it calls execute() rather thanexecuteUpdate().

C. The code does not update the database because the Statement is never closed.

D. The code runs without error.

E. The execute() method returns a boolean.

F. The execute() method returns an int.

65. How many of the following pairs of values can fill in the blanks to comply with thecontract of the hashCode() and equals() methods?

class Sticker { @Override public int hashCode() { return _______________ ; } @Override public boolean equals(Sticker o) { return _______________; }

}

I. 5, false

II. 5, true

III. new Random().nextInt(), false

IV. new Random().nextInt(), true

A. None

B. One

C. Two

D. Three

E. Four

F. None of the above. The code does not compile with any of the options.


package winter; abstract class TShirt { abstract int insulate(); public TShirt() { System.out.print("Starting..."); }}public class Wardrobe { abstract class Sweater extends TShirt { int insulate() {return 5;} } private static void dress() { class Jacket extends Sweater { // v1 int insulate() {return 10;} }; final TShirt outfit = new Jacket() { // v2 int insulate() {return 20;} }; System.out.println("Insulation:"+outfit.insulate()); } public static void main(String... snow) { new Wardrobe().dress(); }}

A. Starting...Insulation:20

B. Starting...Insulation:40

C. The code does not compile because of line v1.

D. The code does not compile because of line v2.

E. The code does not compile for a different reason.

67. Which statements about the following application are true?

1: package armory;2: import java.util.function.*;3: class Shield {}4: public class Sword {5: public class Armor {6: int count;7: public final Function<Shield,Sword,Armor> dress = (h,w) > new Armor();8: public final IntSupplier<Integer> addDragon = () > count++;9: }10: public static void main(String[] knight) {11: final Armor a = new Armor();12: a.dress.apply(new Shield(), new Sword());13: a.addDragon.getAsInt();14: }15: }

I. The lambda expression for dress on line 7 compiles without issue.

II. The lambda expression for addDragon on line 8 compiles without issue.

III. Not counting the lambda expressions on lines 7 and 8, the code does not containany compilation errors.

A. I only

B. I and II only

C. I, II, and III

D. II and III only


68. Which two conditions best describe a thread that appears to be active but isperpetually stuck and never able to finish its task? (Choose two.)

A. Deadlock

B. Livelock

C. Loss of precision

D. Out of memory error

E. Race condition

F. Starvation

69. Which statements are true about the following date/times? (Choose two.)

2017-04-01T17:00+03:00[Africa/Nairobi]

2017-04-01T10:00-05:00[America/Panama]

A. The first date/time is earlier.

B. The second date/time is earlier.

C. Both represent the same date/time.

D. The two date/times are zero hours apart.

E. The two date/times are one hour apart.

F. The two date/times are two hours apart.

70. What is true about the following?

import java.util.*;public class Yellow { public static void main(String[] args) { List list = Arrays.asList("Sunny"); method(list); // c1 } private static void method(Collection<?> x) { //c2 x.forEach(a -> {}); // c3 }}

A. The code doesn’t compile due to line c1.

B. The code doesn’t compile due to line c2.

C. The code doesn’t compile due to line c3.

D. The code compiles and runs without output.


71. What is true about the following code? (Choose two.)

public static void main(String[] args) throws Exception { String url = "jdbc:derby:hats;create=true"; Connection conn = null; Statement stmt = null; try { conn = DriverManager.getConnection(url); stmt = conn.createStatement(); stmt.executeUpdate( "CREATE TABLE caps (name varchar(255), size varchar(1))"); } finally { conn.close(); stmt.close(); }}

A. If using a JDBC 3.0 driver, this code throws an exception.

B. If using a JDBC 4.0 driver, this code throws an exception.

C. The resources are closed in the wrong order.

D. The resources are closed in the right order.

E. The Connection is created incorrectly.

F. The Statement is created incorrectly.

72. How many lines of the following application contain a compilation error?

package puzzle;final interface Finder { default long find() {return 20;}}abstract class Wanda { abstract long find();}final class Waldo extends Wanda implements Finder { long find() {return 40;} public static final void main(String[] pictures) { final Finder f = new Waldo(); System.out.print(f.find()); }}

A. One

B. Two

C. Three

D. None. The code compiles and prints 20 at runtime.

E. None. The code compiles and prints 40 at runtime.


1: package reader;2: import java.util.stream.*;3:4: public class Books {5: public static void main(String[] args) {6: IntStream pages = IntStream.of(200, 300);7: long total = pages.sum();8: long count = pages.count();9: System.out.println(total + "-" + count);10: }11: }

A. 2-2

B. 200-1

C. 500-0

D. 500-2



74. What is the output of executing the following code snippet?

30: ExecutorService e = Executors.newSingleThreadExecutor();31: Runnable r1 = () -> Stream.of(1,2,3).parallel();32: Callable r2 = () -> Stream.of(4,5,6).parallel();33:34: Future<Stream> f1 = e.submit(r1);35: Future<Stream> f2 = e.submit(r2);36:37: Stream<Integer> s = Stream.of(f1.get(),f2.get())38: .flatMap(p -> p)39: .parallelStream();40:41: ConcurrentMap<Boolean,List<Integer>> r =42: s.collect(Collectors.groupingByConcurrent(i -> i%2==0));43: System.out.println(r.get(false).size()+" "+r.get(true).size());

A. 3 3

B. 2 4

C. The code does not compile due to one error.

D. The code does not compile due to two errors.

E. The code does not compile due to three errors.

F. The code compiles but a NullPointerException is thrown at runtime.

75. Fill in the blanks: If your application is__________ , it must first have been__________ with respect to supporting multiple languages.

A. extracted, internationalized

B. extracted, localized

C. internationalized, extracted

D. internationalized, localized

E. localized, extracted

F. localized, internationalized

76. Which statement about the following class is true? Assume the file system is availableand able to be modified.

package forest;import java.io.File;public class CreateTree { public boolean createTree(String tree) { if(new File(tree).exists()) { return true; } else { return new File(tree).mkdir(); }

} public static void main(String[] seeds) { final CreateTree creator = new CreateTree(); System.out.print(creator.createTree("/woods/forest")); }}

A. The class compiles and always prints true at runtime.

B. The class compiles and always prints false at runtime.

C. The class compiles but the output cannot be determined until runtime.

D. The class compiles but may throw an exception at runtime.



1: class SmartWatch extends Watch {2: private String getType() { return "smart watch"; }3: public String getName() {4: return getType() + ",";5: }6: }7: public class Watch {8: private String getType() { return "watch"; }9: public String getName(String suffix) {10: return getType() + suffix;11: }12: public static void main(String[] args) {13: Watch watch = new Watch();14: Watch smartWatch = new SmartWatch();15: System.out.print(watch.getName(","));16: System.out.print(smartWatch.getName(""));17: }18: }

A. smart watch,smart watch

B. smart watch,watch

C. watch,smart watch

D. watch,watch


78. In most of the United States, daylight savings time ends on November 5, 2017 at 02:00a.m., and we repeat that hour. What is the output of the following?

import java.time.*; public class FallBack { public static void main(String[] args) { LocalDate localDate = LocalDate.of(2017, Month.NOVEMBER, 5); LocalTime localTime = LocalTime.of(1, 0);

ZoneId zone = ZoneId.of("America/New_York"); ZonedDateTime z = ZonedDateTime.of(localDate, localTime, zone); for (int i = 0; i < 6; i++) z = z.plusHours(1); System.out.println(z.getHour()); }}

A. 5

B. 6

C. 7



79. Which statements about the following application are true?

package party;import java.util.concurrent.*;public class Plan { private ExecutorService service = Executors.newCachedThreadPool(); public void planEvents() { service.scheduleWithFixedDelay( () -> System.out.print("Check food stock"), 1, TimeUnit.HOURS); service.scheduleAtFixedRate( () -> System.out.print("Check drink stock"), 1, 1000, TimeUnit.SECONDS); service.execute(() -> System.out.print("Take out trash")); }}

I. The scheduleWithFixedDelay() method call compiles.

II. The scheduleAtFixedRate() method call compiles.

III. The execute() method call compiles.

A. I only

B. II only

C. III only

D. I and II

E. I, II, and III


80. Which of the following classes are checked exception? (Choose three.)

A. java.io.NotSerializableException

B. java.lang.AssertionError

C. java.lang.IllegalArgumentException

D. java.sql.SQLException

E. java.text.ParseException

F. java.util.MissingResourceException

81. Which of the following are valid functional interfaces? (Choose two.)

A. interface CanClimb {default void climb() {}

static void climb(int x) {}}

B. interface CanDance {int dance() { return 5;}}

C. interface CanFly {abstract void fly();}

D. interface CanRun {void run();

static double runFaster() {return 2.0;}}

E. interface CanSwim {abstract Long swim();

boolean test();}

82. How many of the following could be valid JDBC URL formats for an imaginary drivernamed magic and a database named box?

I. jdbc;box;magic

II. jdbc;magic;@127.0.0.1:1234

III. jdbc;magic;//@127.0.0.1:1234

IV. jdbc;magic;127.0.0.1:1234/box

V. magic;jdbc;127.0.0.1:1234/box

A. None

B. One

C. Two

D. Three

E. Four

F. Five


Stream<String> s = Stream.of("speak", "bark", "meow", "growl");

Map<Integer, String> map = s.collect(toMap(String::length, k > k));System.out.println(map.size() + " " + map.get(4));

A. 2 bark

B. 2 meow

C. 4 bark

D. 4 meow

E. The output is not guaranteed.



package music;interface DoubleBass { void strum(); default int getVolume() {return 5;}}interface BassGuitar { void strum(); default int getVolume() {return 10;}}class ElectricBass implements DoubleBass, BassGuitar { @Override public void strum() {System.out.print("A");}}public class RockBand { public static void main(String[] strings) { final class MyElectricBass extends ElectricBass { public void strum() {System.out.print("E");} } }}

A. A

B. E

C. The code compiles and runs without issue but does not print anything.

D. One line of code does not compile.

E. Two lines of code do not compile.

F. Three lines of code do not compile.

85. Which NIO.2 Files methods return a Stream? (Choose three.)

A. find()

B. lines()

C. list()

D. listFiles()

E. readAllLines()

F. walkFileTree()

AppendixAnswers to Review Questions

Chapter 1: Java Basics1. D. An entry point in a Java application consists of a main() method with a single

String[] argument, return type of void, and modifiers public and static. The nameof the variable in the input argument does not matter. Option A is missing the staticmodifier, Option B is missing the String[] argument, and Option C has the wrongaccess modifier and method name. Only Option D fulfills these requirements. Notethat the modifier final is optional and may be added to an entry point method.

2. A. The diagram is an example of object-oriented design in Java, making Option B atrue statement. Options C and D are also true, as they follow from the inheritancemodel in the diagram. Option A is the correct answer, since platform independencehas nothing to do with the diagram.

3. C. The proper extension for a Java compiled bytecode file is .class, making Option Cthe correct answer.

4. B. The fact that the Date class exists in both packages does not impact the ability toimport both packages, so lines 1 and 2 compile without issue, and Option A isincorrect. Line 4 will not compile because the Date class used is ambiguous, makingOption B correct and Option D incorrect. Finally, Option C is incorrect because line 5does compile, as the fully qualified name of the class is used.

5. A. Options B, C, and D are each attributes of traditional object-oriented programming.Option A is incorrect as an object-oriented project tends to group data and the actionsrelated to that data into a single object.

6. D. Only local variables have such a small scope, making Option D the correct answer.

7. B. The package java.lang is imported into every Java class, so Option B is correct. Theother options must be explicitly imported. Option A exists but must be explicitlyimported. Options C and D do not exist in the standard Java runtime.

8. C. Java accepts Options A, B, and D as valid comments. Note that the /* */ syntax canhave additional (and uneven) star (*) characters as shown in B and D. Option C isincorrect as hashtag (#) is not a valid comment character in Java.

9. D. A valid .java file may define any number of classes or interfaces but have at mostone public class. It can also not define any public classes. For these reasons, OptionA, B, and C are incorrect, leaving Option D as the only correct answer.

10. B. Notice in this question that main() is not a static method, therefore it can accessboth class and instance variables. Since there are two class variables and two instancevariables defined, Option B is the correct answer.

11. B. A class will compile if it has unused or redundant import statements, makingOption A and C incorrect. Option D is also incorrect as the compiler must be able tolocate the class of the import statement. The correct answer is Option B. Removingunused import statements does not cause a class to become unable to be compiled.

12. A. The code does not compile because of line 5, making Option A the correct answer.For this question, it helps to understand variable scope. The main() method is staticand does not have access to any class instance variables. The birds variable is notstatic and requires a class instance variable to access. Therefore, the code does notcompile when the static method attempts to access a non-static variable without aninstance of the class.

13. D. The java command can only execute compiled .class files, so I is false. Java ismost certainly object oriented, one of the key design principles, so II is also false. Thejavac command compiles into bytecode, which must be run in a Java virtual machine(JVM), and is not native machine code, so III is false as well. Since none of thestatements are true, Option D is the correct answer.

14. D. A class can start with a comment, an optional package statement, or an importstatement if there is no package statement. It cannot start with a variable definition,making Option D the correct answer.

15. C. Classes may be defined without a package declaration and are placed in the defaultpackage, so Option A is incorrect. Option B is a completely false statement as no suchfile is required in Java. Option C is correct as it is one of the primary reasons fororganizing your application into packages. Option D is incorrect as package-privateallows access to methods and variables to be limited to those classes within the samepackage.

16. B. The compilation command requires the full or relative name of the file, includingthe .java extension, making Options A and C incorrect. The execution commandrequires the class name without a filename extension, making Option D incorrect.Option B is the only correct set of compilation and execution commands.

17. D. Encapsulation is the technique of removing access to a class’s instance variablesfrom processes outside the class, making Option D the correct answer.

18. D. The height variable is declared within the if-then statement block. Therefore, itcannot be referenced outside the if-then statement and the code does not compile.

19. A. A Java bytecode file is a binary encoded set of instructions designed to be run onany computer with a compatible JVM, making Option A the only correct answer. Bycompatible JVM, we mean one capable of running the class file. For example, a Java 6JVM may have trouble executing a Java 8 compiled file. Option B is incorrect, and ismore a facet of machine language compiled programming classes. Option C is alsoincorrect as binary data is not particularly human readable. Finally, Option D isincorrect as the compiled file can be distributed without its .java source file andexecute without issue.

20. D. Unlike with some other programming languages, the proper way to terminate a lineof code is with a semicolon (;), making D the only correct answer.

21. C. The code compiles and runs without issue, so Options A and B are incorrect. The

question relies on your ability to understand variable scope. The variable today haslocal scope to the method in which it is executed. The variable tomorrow is re-declaredin the method, but the reference used on line 7 is to the instance variable with a valueof 10. Finally, the variable tomorrow is static. While using an instance reference toaccess a static variable is not recommended, it does not prevent the variable frombeing read. The result is line 7 evaluates and prints (20 + 10 + 1) = 31, making C thecorrect answer.

22. C. Line 1 is missing the class keyword. Line 2 contains two types for the samevariable. Line 3 is a valid definition for a method, making C the correct answer.Finally, line 4 contains an access modifier, private, after the return type, which is notallowed. In addition, void is an invalid type for variables.

23. D. Platform independence is the property of Java that allows it to be run on a varietyof different devices.

24. A. Options B, C, and D are each correct statements about JVMs. Option A is incorrect.Not only is it not a statement about JVMs, it is actually false as Java bytecode canoften be easily decoded/decompiled.

25. B. There is no such thing as package variables, so Option A is incorrect. Option C isincorrect as the variable is only in scope within a specific instance of the class. OptionD is also incorrect as the variable is only in scope for a single method that it is definedin. Option B is the only correct answer as class variables are in scope within theprogram.

26. C. Option A is incorrect as the sub-package recurring is not included by the importstatements. Option B is also incorrect as it uses the plural directors instead of thesingular director used in the import statements. Option D is incorrect as the wildcardis applied to the sub-package movie.director, not the package movie. Finally, Option Cis correct as it is a valid class accessible from the wildcard import.

27. D. Java classes are defined in this order: package statement, import statements, classdeclaration, making Option D the only correct answer. Note that not all of thesestatements are required. For example, a class may not have a package statement, but ifit does, it must come first in the file.

28. D. The import statements for stars.* and stars.Blackhole are redundant importstatements, since only the class Blackhole is used, and therefore one of them can besafely removed. The import statements java.lang.* and java.lang.Object are bothnot required as java.lang is automatically imported in every Java class. Therefore,three of the four import statements can be safely removed, making the correct answerOption D.

29. C. The application prints the third argument of the input methods. Note that doublequotes "" group input arguments. Therefore, the third argument of Option A is White-tailed deer. The third argument of Option B is 3. The third argument of Option C isWhite-tailed, making it the correct answer. Finally, Option D only has two input

arguments, leading to an ArrayIndexOutOfBoundsException trying to read the thirdargument at runtime.

30. B. The javac command compiles a .java file into a .class bytecode file, makingOption B the correct answer.

31. B. Java is object oriented, not procedural, so Option A is a false statement. Java allowsmethod overloading in subclasses, so Option B is correct. Operator overloading ispermitted in languages like C++, not Java, so Option C is also untrue. Finally, OptionD is not a true statement as the JVM manages the location of objects in memory thatcan change and is transparent to the Java application.

32. D. Option A is incorrect as the return type of the method cannot be null. Option B isalso incorrect as the return type cannot be void if the method uses a return statement.Option C is incorrect too as the class keyword is replaced with int. Option D is correctbecause it’s the only answer that allows the code to compile without issue. Note thatother values are possible for this question. For example, either int or long can beentered in the last blank. The key here is that only one of the available answer choicesallows the code to compile.

33. A. The code compiles so Option D is incorrect. The input to the constructor is ignored,making the assignment of end to be 4. Since start is 2, the subtraction of 4 by 2 resultsin the application printing 2, followed by 5, making Option A the correct answer.

34. D. Option A is a false statement, while Options B and C are actually arguments againstusing inheritance. Option D is one of the most important reasons Java supportsinheritance, to allow increased code reuse among classes.

35. A. The double slash (//) syntax can have any number of slashes as a comment, so longas it starts with two of them, making Option A the correct answer. The (#) is not acomment character in Java, regardless of whether it is followed by a (!), so Option B isincorrect. Option C is incorrect as a single slash (/) is not a valid comment in Java.Finally, Option D is incorrect as Option A is a valid comment.

36. B. An entry point in a Java application consists of a main() method with a singleString[] argument, return type of void, and modifiers public and static. Option D isthe typical syntax for this method, although Options A and C are also valid forms ofthis method. Note that the modifier final is optional and may be added to the methodsignature. Furthermore, the main() method may take a vararg or array. Option B is theonly invalid declaration as it does not take an array as an argument.

37. B. The line of code cannot be inserted at a1 because no variables are allowed outside ofthe class declaration in this file, making Options A and D incorrect. The line of codecan also not be inserted at a3 as local variables defined within methods cannot haveaccess modifiers such as public, making Option C incorrect. The code can be insertedindependently at a2 and a4 as instance variables can be defined anywhere in the classoutside a method. Therefore, Option B is the correct choice.

38. A. Option A is the only correct answer as a class definition is the only requiredcomponent in a Java class file. Note that we said a Java class file here; Java also allowsinterfaces and enums to be defined in a file. A package statement and importstatements are optional for declaring a class, making Options B and C incorrect. Aclass may also be defined with package-level access in a file, making Option D anincorrect answer.

39. D. The proper extension for a Java compiled bytecode file is .java, making Option Dthe correct answer.

40. C. Remember that java.lang is automatically imported in all Java classes, thereforeboth java.lang.Math and pocket.complex.Math are both imported into this class.Importing both sets of packages does not cause any compilation issues, makingOption A incorrect. Line 3 is unnecessary import but including it does not prevent theclass from compiling, making Option B incorrect. While both versions of Math may beimported into the class, the usage of the Math class requires a package name. Becauseof this, line 6 does not compile as the class reference is ambiguous, making Option Cthe correct answer and Option D incorrect.

41. A. Options B and C are accessible within the class as they are covered by the importstatements. Option D is also fine as java.lang.Object is available without an explicitimport. The only class not automatically accessible within the class without the fullpackage name is dog.puppy.female.KC as the import statements do not include sub-packages; therefore, Option A is the correct answer.

42. B. Object-oriented programming is the technique of structuring data into objects,which may contain data and a set of actions that operate on the data, making Option Bthe correct answer.

43. A. All of the import statements in this class are required. Removing any of them wouldcause the class to not compile, making Option A the correct answer.

44. C. The numLock variable is not accessible in the static main() method without aninstance of the Keyboard class; therefore, the code does not compile, and Option C isthe correct answer.

45. D. The code compiles and runs without issue, so Option A is incorrect. The questioninvolves understanding the value and scope of each variable at the print() statement.The variables feet and tracks are locally scoped and set to 4 and 15, respectively,ignoring the value of tracks of 5 in the instance of the class. Finally, the staticvariable s.wheels has a value of 1. The result is the combined value is 20, makingOption D the correct answer.

46. B. First off, the color variable defined in the instance and set to red is ignored in themethod printColor() as local scope overrides instance scope, so Option A is incorrect.The value of color passed to the printColor() method is blue, but that is lost by theassignment to purple, making Option B the correct answer and Option C incorrect.Option D is incorrect as the code compiles and runs without issue.

47. C. The javac command takes a text-based .java file and returns a binary bytecode.class file, making II a true statement. The java command uses a period (.) toseparate packages, not a slash (/), making I a true statement and III a false statement.For these reasons, Option C is the correct answer.

48. D. The application compiles without issue, so Option C is incorrect. The applicationdoes not execute though, as the main() method does not have the correct methodsignature. It is missing the required input argument, an array of String. Trying toexecute the application without a proper entry point produces an error, making OptionD the correct answer.

49. C. Option A does not compile because it is missing the closing bracket for the class.Option D does also not compile as void is not a valid type for a variable. Regardless,Options A and D are incorrect as they are missing the getRating() method. Note thatOption A also uses an abbreviation for numberOfPages. Option B is incorrect as it ismissing the numberOfPages attribute. Option C is the correct answer as it properlydefines the attribute numberOfPages and method getRating().

50. C. Garbage collection can happen at any time while an application is running,especially if the available memory suddenly becomes low, making Option A incorrect.Option B is also incorrect, since it is trivial to create a Java application with an infiniteloop that never terminates. Option D is incorrect because the computer must be ableto run the JVM in order to execute a Java class. Option C is the only correct answer, asthe JVM does require an entry point method to begin executing the application.

Chapter 2: Working with Java Data Types1. A. Option A does not compile because Java does not allow declaring different types as

part of the same declaration. The other three options show various legal combinationsof combining multiple variables in the same declarations with optional default values.

2. D. The table variable is initialized to "metal". However, chair is not initialized. InJava, initialization is per variable and not for all the variables in a single declaration.Therefore, the second line tries to reference an uninitialized local variable and doesnot compile, which makes Option D correct.

3. B. Instance variables have a default value based on the type. For any non-primitive,including String, that type is a reference to null. Therefore Option B is correct. If thevariable was a local variable, Option C would be correct.

4. B. An identifier name must begin with a letter, $, or _. Numbers are only permitted forsubsequent characters. Therefore, Option B is not a valid variable name.

5. B. In Java, class names begin with an uppercase letter by convention. Then they uselowercase with the exception of new words. Option B follows this convention and iscorrect. Option A follows the convention for variable names. Option C follows theconvention for constants. Option D doesn’t follow any Java conventions.

6. C. Objects have instance methods while primitives do not. Since int is a primitive, youcannot call instance methods on it. Integer and String are both objects and haveinstance methods. Therefore, Option C is correct.

7. C. Underscores are allowed between any two digits in a numeric literal. Underscoresare not allowed at the beginning or end of the literal, making Option C the correctanswer.

8. C. Option A is incorrect because int is a primitive. Option B is incorrect because it isnot the name of a class in Java. While Option D is a class in Java, it is not a wrapperclass because it does not map to a primitive. Therefore, Option C is correct.

9. C. There is no class named integer. There is a primitive int and a class Integer.Therefore, the code does not compile, and Option C is correct. If the type was changedto Integer, Option B would be correct.

10. C. The new keyword is used to call the constructor for a class and instantiate aninstance of the class. A primitive cannot be created using the new keyword. Dealingwith references happens after the object created by new is returned.

11. D. Java uses the suffix f to indicate a number is a float. Java automatically widens atype, allowing a float to be assigned to either a float or a double. This makes bothlines p1 and p3 compile. Line p2 does compile without a suffix. Line p4 does notcompile without a suffix and therefore is the answer.

12. A. A byte is smaller than a char, making Option C incorrect. bigint is not a primitive,

making Option D incorrect. A double uses twice as much memory as a float variable,therefore Option A is correct.

13. D. The instance variables, constructor, and method names can appear in any orderwithin a class declaration.

14. B. Java does not allow multiple Java data types to be declared in the same declaration,making Option B the correct answer. If double was removed, both hot and cold wouldbe the same type. Then the compiler error would be on x3 because of a reference to anuninitialized variable.

15. C. Lines 2 and 7 illustrate instance initializers. Line 6 is a static initializer. Lines 3–5are a constructor.

16. A. Since defaultValue is a local variable, it is not automatically initialized. That meansthe code will not compile with any type. Therefore, Option A is correct. If this was aninstance variable, Option C would be correct as int and short would be initialized to 0while double would be initialized to 0.0.

17. A. The finalize() method may not be called, such as if your program crashes.However, it is guaranteed to be called no more than once.

18. D. String is a class, but it is not a wrapper class. In order to be a wrapper class, theclass must have a one-to-one mapping with a primitive.

19. C. Lines 15–17 create the three objects. Lines 18–19 change the references so link2and link3 point to each other. The lines 20–21 wipe out two of the original references.This means the object with name as x is inaccessible.

20. C. Options A and D are incorrect because byte and short do not store values withdecimal points. Option B is tempting. However, 3.14 is automatically a double. Itrequires casting to float or writing 3.14f in order to be assigned to a float. Therefore,Option C is correct.

21. B. Integer is the name of a class in Java. While it is bad practice to use the name of aclass as your local variable name, this is legal. Therefore, k1 does compile. It is notlegal to use a reserved word as a variable name. All of the primitives including int arereserved words. Therefore, k2 does not compile, and Option B is the answer. Line k4doesn’t compile either, but the question asks about the first line to not compile.

22. B. Dot notation is used for both reading and writing instance variables, assuming theyare in scope. It cannot be used for referencing local variables, making Option B thecorrect answer.

23. C. Class names follow the same requirements as other identifiers. Underscores anddollar signs are allowed. Numbers are allowed, but not as the first character of anidentifier. Therefore, Option C is correct. Note that class names begin with anuppercase letter by convention, but this is not a requirement.

24. D. This question is tricky as it appears to be about primitive vs. wrapper classes.

Looking closely, there is an underscore right before the decimal point. This is illegal asthe underscore in a numeric literal can only appear between two digits.

25. C. Local variables do not have a default initialization value. If they are referencedbefore being set to a value, the code does not compile. Therefore, Option C is correct.If the variable was an instance variable, Option B would be correct. Option D is tricky.A local variable will compile without an initialization if it isn’t referenced anywhere orit is assigned a value before it is referenced.

26. C. Since defaultValue is an instance variable, it is automatically initialized to thecorresponding value for that type. For double, that value is 0.0. By contrast, it is 0 forint, long, and short. Therefore Option C is correct.

27. B. Option B is an example of autoboxing. Java will automatically convert fromprimitive to wrapper class types and vice versa. Option A is incorrect because you canonly call methods on an object. Option C is incorrect because this method is used forconverting to a wrapper class from a String. Option D is incorrect because autoboxingwill convert the primitive to an object before adding it to the ArrayList.

28. C. Java does not allow calling a method on a primitive. While autoboxing does allowthe assignment of an Integer to an int, it does not allow calling an instance methodon a primitive. Therefore, the last line does not compile.

29. D. In order to call a constructor, you must use the new keyword. It cannot be called asif it was a normal method. This rules out Options A and B. Further, Option C isincorrect because the parentheses are required.

30. A. Option A (I) correctly assigns the value to both variables. II does not compile as dogdoes not have a type. Notice the semicolon in that line, which starts a new statement.III compiles but only assigns the value to dog since a declaration only assigns to onevariable rather than everything in the declaration. IV does not compile because thetype should only be specified once per declaration.

31. C. The wrapper class for int is Integer and the wrapper class for char is Character. Allother primitives have the same name. For example, the wrapper class for boolean isBoolean.

32. A. Assuming the variables are not primitives, they allow a null assignment. The otherstatements are false.

33. A. An example of a primitive type is int. All the primitive types are lowercase, makingOption A correct. Unlike object reference variables, primitives cannot reference null.String is not a primitive as evidenced by the uppercase letter in the name and the factthat we can call methods on it. You can create your own classes, but not primitives.

34. D. While you can suggest to the JVM that it might want to run a garbage collectioncycle, the JVM is free to ignore your suggestion. Option B is how to make thissuggestion. Since garbage collection is not guaranteed to run, Option D is correct.

35. C. All three references point to the String apple. This makes the other two Stringobjects eligible for garbage collection and Option C correct.

36. B. A constructor can only be called with a class name rather than a primitive, makingOptions A and C incorrect. The newly constructed Double object can be assigned toeither a double or Double thanks to autoboxing. Therefore, Option B is correct.

37. B. First line 2 runs and sets the variable using the declaration. Then the instanceinitializer on line 6 runs. Finally, the constructor runs. Since the constructor is the lastto run of the three, that is the value that is set when we print the result, so Option B iscorrect.

38. C. Objects are allowed to have a null reference while primitives cannot. int is aprimitive, so assigning null to it does not compile. Integer and String are bothobjects and can therefore be assigned a null reference. Therefore, Option C is correct.

39. C. An instance variable can only be referenced from instance methods in the class. Astatic variable can be referenced from any method. Therefore, Option C is correct.

40. B. Underscores are allowed between any two digits in a numeric literal. Underscoresare not allowed adjacent to a decimal point, making Option B the correct answer.

41. A. These four types represent nondecimal values. While you don’t need to know theexact sizes, you do need to be able to order them from largest to smallest. A byte issmallest. A short comes next, followed by int and then long. Therefore, Option A iscorrect.

42. A. Java uses dot notation to reference instance variables in a class, making Option Acorrect.

43. B. If there was a finalize() method, this would be a different story. However, themethod here is finalizer. Tricky! That’s just a normal method that doesn’t get calledautomatically. Therefore clean is never output.

44. A. Options B and C do not compile. In Java, braces are for arrays rather than instancevariables. Option A is the correct answer. It uses dot notation to access the instancevariable. It also shows that a private variable is accessible in the same class and that anarrower type is allowed to be assigned to a wider type.

45. B. The parseInt() methods return a primitive. The valueOf() methods return awrapper class object. In real code, autoboxing would let you assign the return value toeither a primitive or wrapper class. In terms of what gets returned directly, Option B iscorrect.

46. B. On line 9, all three objects have references. The elena and zoe objects have a directreference. The diana object is referenced through the elena object. On line 10, thereference to the diana object is replaced by a reference to the zoe object. Therefore, thediana object is eligible to be garbage collected, and Option B is correct.

47. C. Options A and B are static methods rather than constructors. Option D is a method

that happens to have the same name as the class. It is not a constructor becauseconstructors don’t have return types.

48. A. Remember that garbage collection is not guaranteed to run on demand. If it doesn’trun at all, Option B would be output. If it runs at the requested point, Option C wouldbe output. If it runs right at the end of the main() method, Option D would be output.Option A is the correct answer because play is definitely called twice. Note that youare unlikely to see all these scenarios if you run this code because we have not usedenough memory for garbage collection to be worth running. However, you still need tobe able to answer what could happen regardless of it being unlikely.

49. B. Each wrapper class has a constructor that takes the primitive equivalent. Themethods mentioned in Options A, C, and D do not exist.

50. C. The main() method calls the constructor which outputs a. Then the main methodcalls the run() method. The run() method calls the constructor again, which outputs aagain. Then the run() method calls the Sand() method, which happens to have thesame name as the constructor. This outputs b. Therefore, Option C is correct.

Chapter 3: Using Operators and Decision Constructs1. B. A switch statement supports the primitive types byte, short, char, and int and the

classes String, Character, Byte, Short, and Integer. It also supports enumeratedtypes. Floating-point types like float and double are not supported, therefore OptionB is the correct answer.

2. A. Remember that in ternary expressions, only one of the two right-most expressionsare evaluated. Since meal>6 is false, ––tip is evaluated and ++tip is skipped. Theresult is that tip is changed from 2 to 1, making Option A the correct answer. Thevalue of total is 6, since the pre-increment operator was used on tip, although youdid not need to know this to solve the question.

3. C. The first assignment creates a new String "john" object. The second line explicitlyuses the new keyword, meaning a new String object is created. Since these objects arenot the same, the == test on them evaluates to false. The equals() test on themreturns true because the values they refer to are equivalent. Therefore, the correctanswer is C.

4. D. This code does not compile because it has two else statements as part of a single if-then statement. Notice that the second if statement is not connected to the last elsestatement. For this reason, Option D, none of the above, is the correct answer.

5. C. A default statement inside a switch statement is optional and can be placed in anyorder within the switch’s case statements, making Options A and B incorrect. OptionD is an incorrect statement as a switch statement can be composed of a single defaultstatement and no case statements. Option C is correct because a default statementdoes not take a value, unlike a case statement.

6. B. The initial assignment of thatNumber follows the first branch of the ternaryexpression. Since 5 >= 5 evaluates to true, a value of 3 is assigned to thatNumber. Inthe next line, the pre-increment operator increments the value of thatNumber to 4 andreturns a value of 4 to the expression. Since 4 < 4 evaluates to false, the if-then blockis skipped. This leaves the value of thatNumber as 4, making Option B the correctanswer.

7. B. The break statement exits a switch statement, skipping all remaining branches,making Option B the correct answer. In Option A, exit is not a statement in Java. InOption C, goto is a reserved word but unused in Java. Finally, in Option D, continue isa statement but only used for loops.

8. C. Option A is incorrect as only one of the two right-hand expressions is evaluated atruntime. Parentheses are often helpful for reading ternary expressions but are notrequired, making Option B incorrect. Option C is a correct statement about ternaryoperators as they are commonly used to replace short if-then-else statements. Finally,Option D is incorrect as only boolean expressions are permitted in the left-mostoperand of a ternary expression.

9. C. On line 4, candidateA and candidateB are numbers, but the && operation can only beapplied to boolean expressions. Therefore, the code does not compile because of line 4,making C the correct answer. All of the other lines are correct. Note that if line 4 isfixed, line 3 does not produce a NullPointerException at runtime. The conditional ||and the preceding null check allows the code to only call intValue() if candidateA isnot null.

10. A. The first step is to determine whether or not the if-then statement’s expression isexecuted. The expression 6 % 3 evaluates to 0, since there is no remainder, and since 0>= 1 is false, the expression triceratops++ is not called. Notice there are no brackets{} in the if-then statement. Despite the triceratops–– line being indented, it is notpart of the if-then statement. Recall that Java does not use indentation to determinethe beginning or end of a statement. Therefore, triceratops–– is always executed,resulting in a value of 2 for triceratops and making Option A the correct answer.

11. D. Option A is incorrect because else statements are entirely optional. Option B is alsoincorrect. The target of an if-then statement is not evaluated if the boolean test isfalse. Option C is incorrect. While an if-then statement is often used to test whetheran object is of a particular type in order to cast it, it is not required to cast an object.Option D is correct as an if-then statement may execute a single statement or a blockof code {}.

12. D. For this question, it helps to notice that the second if-then statement is notconnected to the first if-then statement, as there is no else joining them. When thiscode executes, the first if-then statement outputs Not enough since flair is >= 15 and< 37. The second if-then statement is then evaluated. Since flair is not 37, theexpression Too many is outputted. Since two statements are outputted, Option D, noneof the above, is the correct answer.

13. B. A case value must be a constant expression, such as a literal or final variable, soOptions A and C are true statements about case values. A case statement may beterminated by a break statement, but it is not required, making Option B the falsestatement and correct answer. Option D is also a true statement about case values.

14. D. The question is about boolean operators. Since Options A and B are numericoperators, they can be instantly disregarded. The question then simplifies to whichboolean expression, && or ||, corresponds to the truth table that only evaluates to trueif both operands are true. Only the conjunctive logical && operator represents thisrelationship, making Option D the correct answer.

15. C. The value of jumps and hops is unimportant because this code does not compile,making Option C the correct answer. Unlike some other programming languages, Javadoes not automatically convert integers to boolean values for use in if-thenstatements. The statement if(jumps) evaluates to if(0), and since 0 is not a booleanvalue, the code does not compile. Note that the value of the jumps variable is irrelevantin this example; no integer evaluates to a boolean value in Java.

16. B. Prefix operators modify the variable and evaluate to the new value, while postfixoperators modify the variable but return the original value. Therefore, Option B is thecorrect answer.

17. B. For this problem, it helps to recognize that parentheses take precedence over theoperations outside the parentheses. Once we replace the variables with values, theexpression becomes: 3+2*(2+3). We then calculate the value inside the parentheses toget 3+2*5. Since the multiplication operator has higher precedence than addition, weevaluate it first, resulting in 3+10 = 13, making Option B the correct answer.

18. B. Any value that can be implicitly promoted to int will work for the case statementwith an int input. Since switch statements do not support long values, and longcannot be converted to int without a possible loss of data, Option B is the correctanswer.

19. D. While parentheses are recommended for ternary operations, especially embeddedones, they are not required, so Option C is incorrect. The code does not compilebecause day is an int, not a boolean expression, in the second ternary operation,making Option D the correct answer. Remember that in Java, numeric values are notaccepted in place of boolean expressions in if-then statements or ternary operations.

20. C. While the code involves numerous operations, none of that matters for solving thisproblem. The key to solving it is to notice that the line that assigns the leadersvariable has an uneven number of parentheses. Without balanced parentheses, thecode will not compile, making Option C the correct answer.

21. B. Remember that Java evaluates + from left to right. The first two values are bothnumbers, so the + is evaluated as numeric addition, resulting in a reduction to 11 +"7" + 8 + 9. The next two terms, 11 + "7", are handled as string concatenation sinceone of the terms is a String. This allows us to reduce the expression to "117" + 8 + 9.Likewise, the final two terms are each evaluated one at a time with the String on theleft. Therefore, the final value is 11789, making Option B the correct answer.

22. B. The subtraction - operator is used to find the difference between two numbers,while the modulus % operator is used to find the remainder when one number isdivided by another, making Option B the correct answer. The other options useoperators that do not match this description.

23. B. The code compiles without issue, making Option D incorrect. The focus of thisquestion is showing how the division and modulus of two numbers can be used toreconstitute one of the original operands. In this example, partA is the integer divisionof the two numbers. Since 3 does not divide 11 evenly, it is rounded down to 3. Thevariable partB is the remainder from the first expression, which is 2. The newDogvariable is an expression that reconstitutes the original value for dog using the divisionvalue and the remainder. Note that due to operator precedence, the multiplication *operation is evaluated before the addition + operation. The result is the original valueof 11 for dog is outputted by this program.

24. B. The code compiles without issue, so Option D is incorrect. In this question’s switchstatement, there are no break statements. Once the matching case statement, 30, isreached, all remaining case statements will be executed. The variable eaten isincreased by 1, then 2, then reduced by 1, resulting in a final value of 2, making OptionB the correct answer.

25. C. Ternary operations require both right-hand expressions to be of compatible datatypes. In this example, the first right-hand expression of the outer ternary operation isof type String, while the second right-hand expression is of type int. Since these datatypes are incompatible, the code does not compile, and Option C is the correct answer.

26. A. For this question, remember that if two String objects evaluate to true using ==,then they are the same object. If they are the same String object, equals() willtrivially return true. Option A correctly reflects this principle. Option B is incorrect astwo String objects that are not the same may still be equivalent in terms of equals().For example, apples == new String(apples) evaluates to false, but equals() willevaluate to true on these String objects. Likewise, Options C and D are also incorrectbecause two String objects that are equivalent in terms of equals() may be differentobjects.

27. B. The statement compiles and runs without issue, making Options C and D incorrect.Since we are given that myTestVariable is not null, the statement will always evaluateto false, making Option B the correct answer. Note that if myTestVariable was null,then the code would still compile but throw a NullPointerException calling equals()at runtime.

28. D. The code does not compile, making Option D the correct answer. The reason thecode does not compile is due to the test in the second if-then statement. Theexpression (streets && intersections > 1000) is invalid because streets is not aboolean expression and cannot be used as the left-hand side of the conjunctive logical&& operator. The line of code is designed to resemble the corrected expression(streets > 1000 && intersections > 1000. Notice the fixed expression requires tworelational > operators. If the second if-then statement was corrected, then theapplication would compile and produce two 1’s, making Option C the correct answer.

29. B. The & and && (AND) operators are not interchangeable, as the conjunctive & operatoralways evaluates both sides of the expression, while the conditional conjunctive &&operator only evaluates the right-hand side of the expression if the left side isdetermined to be true. This is why conditional operators are often referred to as short-circuit operators, skipping the right-hand side expression at runtime. For thesereasons, Option B is the correct answer. Note that Option C is an incorrect statementas well, since it describes disjunctive (OR) operators.

30. C. The code compiles, so Option A is incorrect. Since w starts out true, the third linetakes the first right-hand side of the ternary expression returning and assigning 5 to x(post-increment operator) while incrementing y to 6. Note that the second right-handside of the ternary expression y–– is not evaluated since ternary operators only

evaluate one right-hand expression at runtime. On the fourth line, the value of w is setto !z. Since z is false, the value of w remains true. The final line outputs the value of(5+6) and (true ? 5 : 10), which is 11 5, making Option C the correct answer.

31. A. The first assignment actually uses two String objects, the literal "bob" and theString created with the new keyword. Regardless, only the second object is assigned tothe variable bob. The second variable, notBob, is assigned a reference to the value ofthe bob variable. This means that not only does the equals() test pass, but they areactually the same object, so the == test is true as well. Therefore, the correct answer isOption A.

32. B. The question is about operator precedence and order of operation. Themultiplication * and modulus % operators have the highest precedence, although whatis inside the parentheses needs to be evaluated first. We can reduce the expression tothe following: 12 + 6 * 3 % 2. Since multiplication * and modulus % have the sameoperator precedence, we evaluate them from left to right as follows: 12 + 6 * 3 % 2 →12 + 18 % 2 → 12 + 0 → 12. We see that despite all of the operators on the right-handside of the expression, the result is zero, leaving us a value of 12, making Option B thecorrect answer.

33. D. The XOR ^ operator evaluates to true if p and q differ and false if they are thesame. Therefore, the missing values are true and false, making Option D the correctanswer.

34. C. The key to understanding this question is to remember that the conditionalconjunction && operator only executes the right-hand side of the expression if the left-hand side of the expression is true. If data is an empty array, then the expression endsearly and nothing is output. The second part of the expression will return true ifdata’s first element is sound or logic. Since we know from the first part of thestatement that data is of length at least one, no exception will be thrown. The finalpart of the expression with data.length<2 doesn’t change the output when data is anarray of size one. Therefore, sound and logic are both possible outputs. For thesereasons, Option C is the only result that is unexpected at runtime.

35. C. In Option A, the division operator / incorrectly comes after the decrement ––operator. In Option B, the subtraction operator - incorrectly comes after the modulus% operator. In Option D, the division operator / incorrectly comes after the subtraction- operator. The correct answer is Option C, where all three operators have the sameorder of precedence.

36. D. The exclusive or (XOR) ^ operator requires evaluating both operands to determinethe result. For this reason, Options A and B are incorrect. For Option B, you can’t havea short-circuit operation if both operands are always read, therefore ^^ does not exist.Option C is an incorrect statement as the ^ operator only returns true if exactly oneoperand is true. Finally, Option D is correct as the ^ is only applied to boolean valuesin Java.

37. C. The diagram represents the overlap of x and y, corresponding to when one of themis true. Therefore, x || y, Option C, most closely matches this relationship. Note thatz is unused in the diagram and therefore is not required in any expression.

38. D. The value of a case statement must be constant, a literal value, or final variable.Since red is missing the final attribute, no variable type allows the code to compile,making Option D the correct answer.

39. C. The question is asking which operator represents greater than or equal to andwhich operator is strictly less than. The >= and < correspond to these operators,respectively. Therefore, Option C is the correct answer. Note that the question doesnot specify which order the operators needed to appear in, only to select the twooperators that match the question description.

40. B. The code compiles and runs without issue, making Options C and D incorrect. Thekey here is understanding operator precedence and applying the parentheses tooverride precedence correctly. The first expression is evaluated as follows: 10 * (2 +(3 + 2) / 5) → 10 * (2 + 5 / 5) → 10 * (2 + 1) → 10 * 3, with a final value of 30for turtle. Since turtle is not less than 5, a value of 25 is assigned to hare. Sinceturtle is not less than hare, the last expression evaluates to Turtle wins!, which isoutputted to the console, making Option B the correct answer.

41. A. All of the terms of getResult() in this question evaluate to 0, since they are all lessthan or equal to 5. The expression can therefore be reduced to 0+0+0+0+"". Since Javaevaluates the + operator from left to right, the four operands on the left are appliedusing numeric addition, resulting in the expression 0+"". This expression just convertsthe value to a String, resulting in an output of 0, making Option A the correct answer.

42. A. The code compiles without issue, so Option D is incorrect. The key here is that theif-then statement in the runTest() method uses the assignment operator (=) insteadof the (==) operator. The result is that spinner is assigned a value of true, and thestatement (spinner = roller) returns the newly assigned value. The method thenreturns up, making Option A the correct answer. If the (==) operator had been used inthe if-then statement, then the process would have branched to the else statement,with down being returned by the method.

43. D. The conditional disjunction (OR) || operator is true if either of the operands aretrue, while the logical complement (!) operator reverses or flips a boolean value,making Option D the correct answer. The other options use operators that do notmatch this description. In particular, Options A and C include operators that can onlybe applied to numerical values, not boolean ones.

44. A. While parentheses are recommended for ternary operations, especially embeddedones, they are not required, so Option C is incorrect.. The first ternary operationevaluates characters <= 4 as false, so the second ternary operation is executed. Sincestory > 1 is true, the final value of movieRating is 2.0, making Option A the correctanswer.

45. B. Barring any JVM limitations, a switch statement can have any number of casestatements (including none) but at most one default statement, with Option Bcorrectly identifying this relationship.

46. A. The application uses the conditional conjunction && operator to test if weather[0] isnull, but unfortunately this test does not work on zero-length arrays. Therefore, it ispossible this code will throw an ArrayIndexOutOfBoundsException at runtime. Thesecond part of the expression evaluates to true if the first input of weather matchessunny. The final part of the expression, && !false, is a tautology in that it is alwaystrue and has no impact on the expression. Either an exception will be thrown or textwill be output, based on the value of weather, therefore Option A is the correct answer.

47. D. The question looks a lot more difficult than it is. In fact, to solve it you don’t haveto compute anything! You just have to notice that the logical complement operator (!),which can only be applied to boolean values, is being applied to a numeric value.Therefore, the answer is that the expression wouldn’t compile or run, making OptionD the correct answer.

48. C. The disjunctive logical || operator evaluates to true if either operand is true.Another way to look at it is that it only evaluates to false if both operands are false.Therefore, the missing values are both true, making Option C the correct answer.

49. A. In Option B, the subtraction operator - incorrectly comes after the decrement ––operator. In Option C, the division operator / incorrectly comes after the increment ++operator. In Option D, the modulus operator % incorrectly comes after the increment++ operator. The correct answer is Option A, where the subtraction - and addition +operators are followed by the division / and multiplication * operators.

50. C. The key to solving this problem is remembering that the type of the value returnedby a ternary operation is determined by the expressions on the right-hand side. Online p1, the expressions are of type int, but the assignment is to the variable game, oftype String. Since the assignment is invalid, the code does not compile, and Option Cis correct.

Chapter 4: Creating and Using Arrays1. B. Three dots (...) are the syntax for a method parameter of type varargs. It is treated

like an array.

2. B. Array indexes are zero based in Java. A varargs parameter is simply another way ofpassing in data to a method. From within the method, it is treated just like you hadwritten Frisbee[] f as the method parameter. Therefore, the first element uses the0th index, and Option B is correct.

3. D. Trick question! While int is a primitive, all arrays are objects. One way to tell isthat an array has a public instance variable called length. Another way is that you canassign it a variable of type Object. Therefore, Option D is correct.

4. C. The array braces are allowed to appear before or after the variable name, makingthe tiger and bear declarations correct. The braces are not allowed to appear beforethe type making the lion declaration incorrect. Therefore, Option C is correct.

5. C. From within a method, an array or varargs parameter is treated the same. However,there is a difference from the caller’s point of view. A varargs parameter can receiveeither an array or individual values, making Options A and B compile. However, anarray parameter can only take an array, which prevents Option C from compiling.

6. A. Arrays use the length variable to determine the number of elements, makingOption A correct. For an ArrayList, Option D would have been the answer.

7. C. A two-dimensional array is declared by listing both sizes in separate pairs of braces.Option C correctly shows this syntax.

8. B. There is nothing wrong with this code. It correctly creates a seven-element array.The loop starts with index 0 and ends with index 6. Each line is correctly output.Therefore, Option B is correct.

9. B. Sorry. This is just something you have to memorize. The sort() andbinarySearch() methods do sorting and searching, respectively.

10. B. The elements of the array are of type String rather than int. Therefore, we usealphabetical order when sorting. The character 1 sorts before the character 9,alphabetically making Option A incorrect. Shorter strings sort before longer stringswhen all the other characters are the same, making Option B the answer.

11. B. Array indices start with 0, making Options C and D incorrect. The length attributerefers to the number of elements in an array. It is one past the last valid array index.Therefore, Option B is correct.

12. C. When using an array initializer, you are not allowed to specify the size separately.The size is inferred from the number of elements listed. Therefore, tiger and ohMy areincorrect. When you’re not using an array initializer, the size is required. An emptyarray initializer is allowed. Option C is correct because lion and bear are legal.

13. B. Since no elements are being provided when creating the arrays, a size is required.Therefore, lion and bear are incorrect. The braces containing the size are required tobe after the type, making ohMy incorrect. The only one that is correct is tiger, makingthe correct answer Option B.

14. C. The binarySearch() method requires a sorted array in order to return a correctresult. If the array is not sorted, the results of a binary search are undefined.

15. A. An ArrayList expands automatically when it is full. An array does not, makingOption A the answer. The other three statements are true of both an array and anArrayList.

16. C. This code creates a two-dimensional array of size 1×2. Lines m1 and m2 assign valuesto both elements in the outer array. Line m3 attempts to reference the second elementof the outer array. Since there is no such position, it throws an exception, and OptionC is correct.

17. B. The code sorts before calling binarySearch(), so it meets the precondition for thatmethod. The target string of "Mac" is the second element in the sorted array. Sincearray indices begin with zero, the second position is index 1, and Option B is correct.

18. A. A multi-dimensional array is created with multiple sets of size parameters. The firstline should be char[] ticTacToe = new char[3][3];. Therefore, Option A is theanswer.

19. B. The first line creates one object; the array itself. While there are four references tonull in that array, none of those are objects. The second line creates one object andpoints one of the array references to it. So far there are two objects: the array itself andone object it is referencing. The third line does the same, bringing up the object countto three. Therefore, Option B is correct.

20. B. As with a one-dimensional array, the braces must be after the type, making alphaand beta illegal declarations. For a multi-dimensional array, the braces are allowed tobe before and/or after the variable name. They do not need to be in the same place.Therefore, the remaining three are correct, and Option B is correct.

21. B. Options A, C and D represent 3x3 2D arrays. Option B best represents the array inthe code. It shows there are three different arrays of different lengths.

22. D. names.length is the number of elements in the array. The last valid index in thearray is one less than names.length. In Java, arrays do not resize automatically.Therefore, the code throws an ArrayIndexOutOfBoundsException.

23. C. The code days.size() would be correct if this was an ArrayList. Since it is an array,days.length is the correct code. Therefore, the code does not compile, and Option C isthe answer.

24. C. Since the braces in the declaration are before the variable names, the variable typeboolean[][][] applies to both variables. Therefore, both bools and moreBools can

reference a 3D array.

25. C. Calling toString() on an array doesn’t output the contents of the array, makingOption C correct. If you wanted Option A to be the answer, you’d have to callArrays.toString(strings).

26. B. Arrays begin with an index of 0. This array is a 3×3 array. Therefore. only indexes 0,1. and 2 are valid. Line r2 throws an ArrayIndexOutOfBoundsException. Therefore.Option B is correct.

27. D. Three dots in a row is a varargs parameter. While varargs is used like an array fromwithin the method, it can only be used as a method parameter. This syntax is notallowed for a variable, making Option D the answer.

28. D. Line 6 assigns an int to a cell in a 2D array. This is fine. Line 7 casts to a generalObject[]. This is dangerous, but legal. Why is it dangerous, you ask? That brings us toline 8. The compiler can’t protect us from assigning a String to the int[] because thereference is more generic. Therefore, line 8 throws an ArrayStoreException becausethe type is incorrect, and Option D is correct. You couldn’t have assigned an int online 8 either because obj[3] is really an int[] behind the scenes and not an int.

29. C. The code sorts before calling binarySearch, so it meets the precondition for thatmethod. The target string of "RedHat" is not found in the sorted array. If it was found,it would be between the second and third element. The rule is to take the negativeindex of where it would be inserted and subtract 1. It would need to be inserted as thethird element. Since indexes are zero based, this is index 2. We take the negative,which is -2, and subtract 1, giving -3. Therefore, Option C is correct.

30. B. Array indexes begin with zero. FirstName is the name of the class, not an argument.Therefore, the first argument is Wolfie, and Option B is correct.

31. C. The name of the program is Count and there are two arguments. Therefore, theprogram outputs 2, and Option C is correct.

32. B. This class is called with two arguments. The first one (seed) is stored in the variableone. Then the array is sorted, meeting the precondition for binary search. Binarysearch returns 1 because seed is the second element in the sorted array, and Java useszero-based indexes. Option B is correct.

33. D. Options A and B show the braces can be before or after the variable name andproduce the same array. Option C specifies the same array the long way with twoarrays of length 1. Option D is the answer because it is different than the others. Itinstead specifies an array of length 1 where that element is of length 2.

34. C. Arrays are indexed using numbers, not strings, making Options A and B incorrect.Since array indexes are zero based, Option C is the answer.

35. D. In Java, arrays are indexed starting with 0. While it is unusual for the loop to startwith 1, this does not cause an error. What does cause an error is the loop ending at

data.length, because the <= operator is used instead of the < operator. The last loopindex is 6, not 7. On the last iteration of the loop, the code throws anArrayIndexOutOfBoundsException. Therefore, Option D is correct.

36. C. Array indexes begin with zero. FirstName is the name of the class, not an argument.The first and only argument is Wolfie. There is not a second argument, so Option C iscorrect.

37. D. This code is correct. Line r1 correctly creates a 2D array. The next three linescorrectly assign a value to an array element. Line r3 correctly outputs 3 in a row!

38. D. Arrays expose a length variable. They do not have a length() method. Therefore,the code does not compile, and Option D is correct.

39. B. This one is tricky since the array braces are split up. This means that bools is a 3Darray reference. The braces both before and after the variable name count. FormoreBools, it is only a 2D array reference because there are only two pairs of bracesnext to the type. In other words, boolean[][] applies to both variables. Then boolsgets another dimension from the braces right after the variable name. However,moreBools stays at 2D, making Option B correct.

40. B. Since no arguments are passed from the command line, this creates an empty array.Sorting an empty array is valid and results in an empty array. Therefore, Option B iscorrect.

41. D. Java requires having a sorted array before calling binarySearch. Since the array isnot sorted, the result is undefined, and Option D is correct. It may happen that you get1 as the result, but this behavior is not guaranteed. You need to know for the examthat this is undefined even if you happen to get the “right” answer.

42. B. Line 8 attempts to store a String in an array meant for an int. Line 8 does notcompile, and Option B is correct.

43. A. This array has two elements, making listing.length output 2. While each arrayelement does not have the same size, this does not matter because we are only lookingat the first element. The first element has one. This makes the answer Option A.

44. C. FirstName is the name of the class, not an argument. There are no other arguments,so names is an empty array. Therefore, Option C is correct.

45. A. In Java, arrays are indexed starting with 0. While it is unusual for the loop to startwith 1, this does not cause an error. It does cause the code to output six lines insteadof seven since the loop doesn’t cover the first array element. Therefore, Option A iscorrect.

46. B. The name of the program is Count, and there is only one argument because doublequotes are used around the value. That argument is a String with three characters: 1,a space, and 2. Therefore, the program outputs 1, and Option B is correct.

47. A. Java requires having a sorted array before calling binarySearch(). You do not have

to call Arrays.sort to perform the sort though. This array happens to already besorted, so it meets the precondition. The target string of "Linux" is the first element inthe array. Since Java uses zero-based indexing, the answer is Option A.

48. A. From within a method, an array parameter and a varargs parameter are treated thesame. From the caller, an array parameter is more restrictive. Both types can receivean array. However, only a varargs parameter is allowed to automatically turnindividual parameters into an array. Therefore, statement I is correct and the answeris Option A.

49. B. All of the variables except nums2b point to a 4D array. Don’t create a 4D array; it’sconfusing. The options show the braces can be before or after the variable in anycombination. Option B is the answer because nums2b points to a 3D array. It only hasthree pairs of braces before the variable and none after. By comparison, nums2a hasthree pairs of braces before the variable and the fourth pair of braces after.

50. C. Binary search returns an int representing the index of a match or where a matchwould be. An int cannot be stored in a String variable. Therefore, the code does notcompile and the answer is Option C.

Chapter 5: Using Loop Constructs1. D. A while loop has a condition that returns a boolean that controls the loop. It

appears at the beginning and is checked before entering the loop. Therefore, Option Dis correct. A traditional for loop also has a boolean condition that is checked beforeentering the loop. However, it is best known for having a counter variable, makingOption B incorrect. Option A is incorrect because the boolean condition on a do-whileloop is at the end of the loop. Option C is incorrect because there is no condition aspart of the loop construct.

2. B. A traditional for loop is best known for having a loop variable counting up or downas the loop progresses. Therefore, Option B is correct. Options A and D are incorrectbecause do-while and while loops are known for their boolean conditions. Option C isincorrect because the for-each loop iterates through without an index.

3. A. A do-while loop checks the loop condition after execution of the loop body. Thisensures it always executes at least once, and Option A is correct. Option B is incorrectbecause there are loops you can write that do not ever enter the loop body, such as for(int i=0;i<1;i++). Similarly, Option D is incorrect because a while loop can bewritten where the initial loop condition is false. Option C is incorrect because a for-each loop does not enter the loop body when iterating over an empty list.

4. C. While a traditional for loop often loops through an array, it uses an index to do so,making Option B incorrect. The for-each loop goes through each element, storing it ina variable. Option C is correct.

5. B. The continue keyword is used to end the loop iteration immediately and resumeexecution at the next iteration. Therefore, Option B is correct. Option A is incorrectbecause the break statement causes execution to proceed after the loop body. OptionsC and D are incorrect because these are not keywords in Java.

6. A. The break keyword is used to end the loop iteration immediately, skip anyremaining executions of the loop, and resume execution immediately after the loop.Therefore, Option A is correct. Option B is incorrect because execution proceeds at thenext execution of the current loop for continue. Options C and D are incorrect becausethese are not keywords in Java.

7. B. A traditional for loop is best known for having an initialization statement,condition statement, and update statement. Option B is correct.

8. C. With a traditional for loop, you control the order in which indexes are visited incode. This means you can loop through an array in ascending or descending order, andOption C is correct.

9. A. With a for-each loop, the loop order is determined for you. With an array, thismeans starting with index 0, and Option A is correct. A traditional for loop allows youto control the order and iterate in either order.

10. A. A do-while loop has a condition that returns a boolean at the end of the loop.Therefore, Option A is correct. Option D is incorrect because a while loop has thiscondition at the beginning of the loop. A traditional for loop is best known for havinga loop variable, making Option B incorrect. Option C is incorrect because there is nocondition as part of the loop construct.

11. B. A while loop requires a boolean condition. While singer is a variable, it is not aboolean. Therefore, the code does not compile, and Option B is correct.

12. B. This is a correct loop to go through an ArrayList or List starting from the end. Itstarts with the last index in the list and goes to the first index in the list. Option B iscorrect.

13. A. The first time through the loop, the index is 0 and glass, is output. The breakstatement then skips all remaining executions on the loop and the main() methodends. If there was no break keyword, this would be an infinite loop because there’s noincrementor.

14. A. Immediately after letters is initialized, the loop condition is checked. The variableletters is of length 0, which is not equal to 2 so the loop is entered. In the loop body,letters becomes length 1 with contents "a". The loop index is checked again and now1 is not equal to 2. The loop is entered and letters becomes length 2 and contains"aa". Then the loop index is checked again. Since the length is now 2, the loop iscompleted and aa is output. Option A is correct.

15. D. There are three arguments passed to the program. This means that i is 3 on thefirst iteration of the loop. The program prints args. Then i is incremented to 4. Whichis also greater than or equal to 0. Since i never gets smaller, this code produces aninfinite loop and the answer is Option D.

16. B. Since count is a class variable that isn’t specifically initialized, it defaults to 0. Onthe first iteration of the loop, "Washington", is 11 characters and count is set to 1. Theif statement’s body is not run. The loop then proceeds to the next iteration. This time,the post-increment operator uses index 1 before setting count to 2. "Monroe" ischecked, which is only 6 characters. The break statement sends the execution to afterthe loop and 2 is output. Option B is correct.

17. C. At first this code appears to be an infinite loop. However, the count variable isdeclared inside the loop. It is not in scope after the loop where it is referenced by theprintln(). Therefore, the code does not compile, and Option C is correct.

18. D. A for loop is allowed to have all three segments left blank. In fact, for(;;) {} is aninfinite loop.

19. C. It is not possible to create an infinite loop using a for-each because it simply loopsthrough an array or ArrayList. The other types allow infinite loops, such as, forexample, do { } while(true), for(;;) and while(true). Therefore, Option C iscorrect. And yes, we know it is possible to create an infinite loop with for-each by

creating your own custom Iterable. This isn’t on the OCA or OCP exam though. If youthink the answer is Option D, this is a great reminder of what not to read into on thereal exam!

20. A. This is a correct loop to go through an ArrayList or List starting from thebeginning. It starts with index 0 and goes to the last index in the list. Option A iscorrect.

21. D. Braces are optional around loops if there is only one statement. Parentheses are notallowed to surround a loop body though, so the code does not compile, and Option D iscorrect.

22. B. The for-each loop uses a variable and colon as the syntax, making Option B correct.

23. C. In this figure, we want to end the inner loop and resume execution at the letterslabel. This means we only want to break out of the inner loop. A break statement doesjust that. It ends the current loop and resumes execution immediately after the loop,making break; a correct answer. The break numbers; statement explicitly says whichloop to end, which does the same thing, making it correct as well. By contrast, breakletters; ends the outer loop, causing the code only to run the println() once.Therefore, two statements correctly match the diagram, and Option C is correct.

24. B. In this figure, we want to end the inner loop and resume execution at the letterslabel. The continue letters; statement does that. The other two statements resumeexecution at the inner loop. Therefore, only the second statement correctly matchesthe diagram, and Option B is correct.

25. C. A while loop checks the boolean condition before entering the loop. In this code,that condition is false, so the loop body is never run. No output is produced, andOption C is correct.

26. C. A for-each loop is allowed to be used with arrays and ArrayList objects.StringBuilder is not an allowed type for this loop, so Option C is the answer.

27. B. This is a correct do-while loop. On the first iteration of the loop, the if statementexecutes and prints inflate-. Then the loop condition is checked. The variableballoonInflated is true, so the loop condition is false and the loop completes.

28. D. Immediately after letters is initialized, the loop condition is checked. The variableletters is of length 0, which is not equal to 3, so the loop is entered. In the loop body,letters becomes length 2 and contains "ab". The loop index is checked again and now2 is not equal to 3. The loop is entered and letters becomes length 4 with contents"abab". Then the loop index is checked again. Since the length 4 is not equal to 3, theloop body is entered again. This repeats for 6, 8, 10, etc. The loop never ends, andOption D is correct.

29. B. In a for loop, the segments are an initialization expression, a boolean conditional,and an update statement in that order. Therefore, Option B is correct.

30. B. On the first iteration through the outer loop, chars becomes 1 element. The innerloop is run once and count becomes 9. On the second iteration through the outer loop,chars becomes 2 elements. The inner loop runs twice so count becomes 7. On the thirditeration through the outer loop, chars becomes 3 elements. The inner loop runs threetimes so count becomes 4. On the fourth iteration through the outer loop, charsbecomes 4 elements. The inner loop runs four times so count becomes 0. Then bothloops end. Therefore, Option B is correct.

31. A. On the first iteration of the outer loop, i starts out at 10. The inner loop sees that 10> 3 and subtracts 3, making the 7 the new value of i. Since 7 > 3, we subtract 3 again,making i set to 4. Yet again 4 > 3, so i becomes 1. Then k is finally incremented to 1.The outer loop decrements i i, making it 0. The boolean condition sees that 0 is notgreater than 0. The outer loop ends and 1 is printed out. Therefore, Option A is correct.

32. D. Options A and C do not compile as they do not use the correct syntax for a for-eachloop. The for-each loop is only able to go through an array in ascending order. It is notable to control the order, making Option C incorrect. Therefore, Option D is theanswer.

33. C. Since there are no brackets around the for statement, the loop body is only oneline. The break statement is not in the loop. Since break cannot be used at the top levelof a method, the code does not compile, and Option C is correct.

34. C. Multiple update expressions are separated with a comma rather than a semicolon.Tricky, we know. But it is an important distinction. This makes Option C correct.

35. D. There are three arguments passed to the program. This means that i is 3 on thefirst iteration of the loop. The program attempts to print args[3]. Since indexes arezero based in Java, it throws an ArrayIndexOutOfBoundsException.

36. B. The first time the loop condition is checked, the variable tie is null. The loop bodyexecutes, setting tie. Despite the indention, there are no brackets surrounding theloop body so the print does not run yet. Then the loop condition is checked and tie isnot null. The print runs after the loop, printing out shoelace once, making Option Bcorrect.

37. C. The code compiles as is. However, we aren’t asked about whether the code compilesas is. Line 27 refers to a loop label. While the label is still present, it no longer pointsto a loop. This causes the code to not compile, and Option C is correct.

38. C. The continue statement is useless here since there is no code later in the loop toskip. The continue statement merely resumes execution at the next iteration of theloop, which is what would happen if the if-then statement was empty. Therefore,count increments for each element of the array. The code outputs 4, and Option C iscorrect.

39. C. A do-while loop requires a boolean condition. The builder variable is aStringBuilder and not a boolean. The code does not compile, and Option C is correct.

40. A. At first this code appears to be an infinite loop. However, there is a break statement.On line 6, count is set to 0. On line 9, it is changed to 1. Then the condition on line 10runs. count is less than 2 so the inner loop continues. Then count is set to 2 on thenext iteration of the inner loop. The loop condition on line 10 runs again and this timeis false. The inner loop is completed. Then line 11 of the outer loop runs and sendsexecution to after the loop on line 13. At this point count is still 2, so Option A iscorrect.

41. C. Option A breaks out of the inner loop, but the outer loop is still infinite. Option Bhas the same problem. Option C is correct because it breaks out of both loops.

42. B. This code is correct. It initializes two variables and uses both variables in thecondition check and the update statements. Since it checks the size of both arrayscorrectly, it prints the first two sets of elements, and Option B is correct.

43. B. Looping through the same list multiple times is allowed. The outer loop executestwice. The inner loop executes twice for each of those iterations of the outer loop.Therefore, the inner loop executes four times, and Option B is correct.

44. B. The initializer, which is alpha, runs first. Then Java checks the condition, which isbeta, to see if loop execution should start. Since beta returns false, the loop is neverentered, and Option B is correct.

45. B. The initializer, which is alpha, runs first. Then Java checks the condition, which isbeta, to see if loop execution should start. Then the loop body, which is delta, runs.After the loop execution, the updater, which is gamma, runs. Then the loop condition,which is beta, is checked again. Therefore, Option B is correct.

46. C. Option A goes through five indexes on the iterations: 0, 1, 2, 3 and 4. Option B alsogoes through five indexes: 1, 2, 3, 4 and 5. Option D goes through five iterations aswell, from 0 to 4. However, Option C goes through six iterations since the loopcondition is at the end of the loop. Therefore it is not like the others, and Option C isthe answer.

47. D. The first time the loop condition is checked, the variable tie is null. However, theloop body is empty due to the semicolon right after the condition. This means the loopcondition keeps running with no opportunity for tie to be set. Therefore, this is aninfinite loop, and Option D is correct.

48. C. Remember to look for basic errors before wasting time tracking the flow. In thiscase, the label of the loop is trying to use the keyword for. This is not allowed, so thecode does not compile. If the label was valid, Option A would be correct.

49. D. On the first iteration of the loop, the if statement executes printing inflate-. Thenthe loop condition is checked. The variable baloonInflated is true, so the loopcondition is true and the loop continues. The if statement no longer runs, but thevariable never changes state again, so the loop doesn’t end.

50. B. In a for loop, the type is only allowed to be specified once. A comma separates

multiple variables since they are part of the same statement. Therefore, Option B iscorrect.

Chapter 6: Working with Methods and Encapsulation1. C. The protected modifier allows access by subclasses and members within the same

package, while the package-private modifier allows access only to members in thesame package. Therefore, the protected access modifier allows access to everythingthe package-private access modifier, plus subclasses, making Option C the correctanswer. Options A, B, and D are incorrect because the first term is a more restrictiveaccess modifier than the second term.

2. B. The super() statement is used to call a constructor in a parent class, while thethis() statement is used to call a constructor in the same class, making Option Bcorrect and Option A incorrect. Options C and D are incorrect because they are notconstructors.

3. D. The sell() method does not compile because it does not return a value if both ofthe if-then statements’ conditional expressions evaluate to false. While logically, it istrue that price is either less than 10 or greater than or equal to 10, the compiler doesnot know that. It just knows that if both if-then statements evaluate to false, then itdoes not have a return value, therefore it does not compile.

4. D. The three overloaded versions of nested() compile without issue, since eachmethod takes a different set of input arguments, making Options B and C incorrect.The code does not compile, though, due to the first line of the main() method, makingOption A incorrect. The no-argument version of the nested() method does not returna value, and trying to output a void return type in the print() method throws anexception at runtime.

5. B. Java uses pass-by-value to copy primitives and references of objects into a method.That means changes to the primitive value or reference in the method are not carriedto the calling method. That said, the data within an object can change, just not theoriginal reference itself. Therefore, Option B is the correct answer, and Options C andD are incorrect. Option A is not a real term.

6. C. Option A is incorrect because the getter should return a value. Option B is incorrectbecause the setter should take a value. Option D is incorrect because the setter shouldstart with set and should not return a value. Option C is a correct setter declarationbecause it takes a value, uses the void return type, and uses the correct namingconvention.

7. B. Options A, C, and D are true statements about calling this() inside a constructor.Option B is incorrect because a constructor can only call this() or super() on the firstline of the constructor, but never both in the same constructor. If both constructorswere allowed to be called, there would be two separate calls to super(), leading toduplicate initialization of parent constructors, since the other constructor referencedby this() would also call super() (or be chained to one that eventually calls super()).

8. B. Option A is incorrect because the public access modifier starts with a lowercase

letter. Options C and D are incorrect because the return types, void and String, areincompatible with the method body that returns an integer value of 10. Option B iscorrect and has package-private access. It also uses a return type of Long that theinteger value of 10 can be easily assigned to without an explicit cast.

9. C. The only variables always available to all instances of the class are those declaredstatic; therefore, Option C is the correct answer. Option A may seem correct, butpublic variables are only available if a reference to the object is maintained among allinstances. Option B is incorrect because there is no local keyword in Java. Option D isalso incorrect because a private instance variable is only accessible within theinstance that created it.

10. A. First off, all of the lines compile but they produce various different results.Remember that the default initialization of a boolean instance variable is false,making outside false at line p1. Therefore, this(4) will cause rope to be set to 5,while this(5) will cause rope to be set to 6. Since 5 is the number we are looking for,Option A is correct, and Option C is incorrect. Option B is incorrect. While thestatement does create a new instance of Jump, with rope having a value of 5, thatinstance is nested and the value of rope does not affect the surrounding instance ofJump that the constructor was called in. Option D is also incorrect. The value assignedto rope is 4, not the target 5.

11. B. Options A, C, and D are true statements. In particular, Option C allows us to writethe equals() methods between two objects that compare private attributes of theclass. Option D is true because protected access also provides package-private access.Option B is false. Package-private attributes are only visible if the two classes are inthe same package, regardless of whether one extends the other.

12. D. The class data, stuff, is declared public, allowing any class to modify the stuffvariable and making the implementation inherently unsafe for encapsulation.Therefore, there are no values that can be placed in the two blanks to ensure the classproperly encapsulates its data, making Option D correct. Note that if stuff wasdeclared private, Options A, B, and C would all be correct. Encapsulation does notrequire JavaBean syntax, just that the internal attributes are protected from outsideaccess, which all of these sets of values do achieve.

13. C. Option A is incorrect because Java only inserts a no-argument constructor if thereare no other constructors in the class. Option B is incorrect because the parent canhave a default no-argument constructor, which is inserted by the compiler andaccessible in the child class. Finally, Option D is incorrect. A class that contains twono-argument constructors will not compile because they would have the samesignature. Finally, Option C is correct. If a class extends a parent class that does notinclude a no-argument constructor, the default no-argument constructor cannot beautomatically inserted into the child class by the compiler. Instead, the developermust explicitly declare at least one constructor and explicitly define how the call to theparent constructor is made.

14. A. A method may contain at most one varargs parameter, and it must appear as thelast argument in the list. For this reason, Option A is correct, and Options B, C, and Dare incorrect.

15. C. To solve this problem, it helps to remember that Java is a pass-by-value language inwhich copies of primitives and object references are sent to methods. This also meansthat an object’s data can be modified within a method and shared with the caller, butnot the reference to the object. Any changes to the object’s reference within themethod are not carried over to the caller. In the slalom() method, the Ski object isupdated with an age value of 18. Although, the last line of the slalom() methodchanges the variable value to null, it does not affect the mySkier object or reference inthe main() method. Therefore, the mySkier object is not null and the age variable is setto 18, making Options A and D incorrect. Next, the name variable is reassigned to theWendy object, but this does not change the reference in the main() method, so myNameremains Rosie. Finally, the speed array is assigned a new object and updated. Since thearray is updated after the reference is reassigned, it does not affect the mySpeed arrayin the main() method. The result is that mySpeed continues to have a single elementwith the default int value of 0. For these reasons, Option B is incorrect, and Option Cis correct.

16. B. Options A and D would not allow the class to compile because two methods in theclass cannot have the same name and arguments, but a different return value. OptionC would allow the class to compile, but it is not a valid overloaded form of ourfindAverage() method since it uses a different method name. Option B is a validoverloaded version of the findAverage() method, since the name is the same but theargument list differs.

17. D. Implementing encapsulation prevents internal attributes of a class from beingmodified directly, so Option C is a true statement. By preventing access to internalattributes, we can also maintain class data integrity between elements, making OptionB a true statement. Option A is also a true statement about encapsulation, since well-encapsulated classes are often easier to use. Option D is an incorrect statement.Encapsulation makes no guarantees about performance and concurrency.

18. A. Option B is incorrect because String values are immutable and cannot be modified.Options C and D are also incorrect since variables are passed by value, not reference,in Java. Option A is the correct answer. The contents of an array can be modified whenpassed to a method, since a copy of the reference to the object is passed. For example,the method can change the first element of a non-empty array.

19. B. Option A is not a valid syntax in Java. Option C would be correct if there was astatic import, but the question specifically says there are not any. Option D is almostcorrect, since it is a way to call the method, but the question asks for the best way tocall the method. In that regard, Option B is the best way to call the method, since weare given that two classes are in the same package, therefore the package name wouldnot be required.

20. D. Options A and B are incorrect because a method with a non-void return typerequires that the method return a value using the return statement. Option C is alsoincorrect since a method with a void return type can still call the return commandwith no values and exit the method. Therefore, Option D is the correct answer.

21. C. The finish() method modifies two variables that are marked final, score andresult. The score variable is modified by the post-increment ++ operator, while theresult variable is modified by the compound addition += operator. Removing bothfinal modifiers allows the code to compile. For this reason, Option C is the correctanswer.

22. D. The super() statement is used to call a constructor in the parent class, while superis used to reference a member of the parent class. The this() statement is used to calla constructor in the current class, while this is used to reference a member of thecurrent class. For these reasons, Option D is the correct answer.

23. B. The method signature has package-private, or default, access; therefore, it isaccessible to classes in the same package, making Option B the correct answer.

24. A. The access modifier of strength is protected, meaning subclasses and classeswithin the same package can modify it. Changing the value to private would improveencapsulation by making the Protect class the only one capable of directly modifyingit. For these reasons, the first statement is correct. Alternatively, the second and thirdstatements do not improve the encapsulation of the class. While having getters andsetters for private variables is helpful, they are not required. Encapsulation is aboutprotecting the data elements. With this in mind, it is clear the material variable isalready protected. Therefore, Option A is the correct answer.

25. A. Option A is correct since method names may include the underscore _ character aswell as the dollar $ symbol. Note that there is no rule that requires a method start witha lowercase character; it is just a practice adopted by the community. Option B isincorrect because the hyphen - character may not be part of a method name. Option Cis incorrect since new is a reserved word in Java. Finally, Option D is incorrect. Amethod name must start with a letter, the dollar $ symbol, or an underscore _character.

26. D. The code does not compile, regardless of what is inserted into the line because themethod signature is invalid. The return type, int, should go before the method nameand after any access, final, or static modifiers. Therefore, Option D is the correctanswer. If the method was fixed, by swapping the order of int and static in themethod declaration, then Option C would be the correct answer. Options A and B arestill incorrect, though, since each uses a return type that cannot be implicitlyconverted to int.

27. B. Java uses pass-by-value, so changes made to primitive values and object referencespassed to a method are not reflected in the calling method. For this reason, Options Aand C are incorrect statements. Option D is also an invalid statement because it is a

special case of Option A. Finally, Option B is the correct answer. Changes to the datawithin an object are visible to the calling method since the object that the copiedreference points to is the same.

28. C. The code contains a compilation problem in regard to the contents instancevariable. The contents instance variable is marked final, but there is a setContents()instance method that can change the value of the variable. Since these two areincompatible, the code does not compile, and Option C is correct. If the final modifierwas removed from the contents variable declaration, then the expected output wouldbe of the form shown in Option A.

29. A. JavaBean methods use the prefixes get, set, and is for boolean values, makingOption A the correct choice.

30. C. Option A is incorrect because the keywords static and import are reversed. TheCloset class uses the method getClothes() without a reference to the class nameStore, therefore a static import is required. For this reason, Option B is incorrectsince it is missing the static keyword. Option D is also incorrect since static importsare used with members of the class, not a class name. Finally, Option C is the correctanswer since it properly imports the method into the class using a static import.

31. D. In Java, the lack of an access modifier indicates that the member is package-private,therefore Option D is correct. Note that the default keyword is used for interfaces andswitch statements, and is not an access modifier.

32. B. The code does not compile, so Option A is incorrect. The class contains twoconstructors and one method. The first method, Stars(), looks a lot like a no-argument constructor, but since it has a return value of void, it is a method, not aconstructor. Since only constructors can call super(), the code does not compile due tothis line. The only constructor in this class, which takes an int value as input,performs a pointless assignment, assigning a variable to itself. While this assignmenthas no effect, it does not prevent the code from compiling. Finally, the main() methodcompiles without issue since we just inserted the full package name into the classconstructor call. This is how a class that does not use an import statement could callthe constructor. Since the method is in the same class, and therefore the samepackage, it is redundant to include the package name but not disallowed. Because onlyone line causes the class to fail to compile, Option B is correct.

33. A. An instance method or constructor has access to all static variables, makingOption A correct. On the other hand, static methods and static initializers cannotreference instance variables since they are defined across all instances, makingOptions B and C incorrect. Note that they can access instance variables if they arepassed a reference to a specific instance, but not in the general case. Finally, Option Dis incorrect because static final variables must be set when they are declared or in astatic initialization block.

34. B. The method calculateDistance() requires a return type that can be easily

converted to a short value. Options A, C, and D are incorrect because they each use alarger data type that requires an explicit cast. Option D also does not compile becausethe Short constructor requires an explicit cast to convert the value of 4, which isassumed to be an int, to a short, as shown in new Short((short)4). Option B is thecorrect answer since a byte value can be easily promoted to short and returned by themethod.

35. C. Overloaded methods have the same name but a different list of parameters, makingthe first and third statements true. The second statement is false, since overloadedmethods can have the same or different return types. Therefore, Option C is thecorrect answer.

36. C. The declaration of monday does not compile, because the value of a static finalvariable must be set when it is declared or in a static initialization block. Thedeclaration of tuesday is fine and compiles without issue. The declaration ofwednesday does not compile because there is no data type for the variable. Finally, thedeclaration of thursday does not compile because the final modifier cannot appearbefore the access modifier. For these reasons, Option C is the correct answer.

37. D. The Puppy class does not declare a constructor, so the default no-argumentconstructor is automatically inserted by the compiler. What looks like a constructor inthe class is actually a method that has a return type of void. Therefore, the line in themain() method to create the new Puppy(2) object does not compile, since there is noconstructor capable of taking an int value, making Option D the correct answer.

38. A. The public modifier allows access to members in the same class, package, subclass,or even classes in other packages, while the private modifier allows access only tomembers in the same class. Therefore, the public access modifier allows access toeverything the private access modifier does, and more, making Option A the correctanswer. Options B, C, and D are incorrect because the first term is a more restrictiveaccess modifier than the second term.

39. A. The code compiles without issue, so Option D is incorrect. The key here is that Javauses pass by value to send object references to methods. Since the Phone reference pwas reassigned in the first line of the sendHome() method, any changes to the preference were made to a new object. In other words, no changes in the sendHome()method affected the object that was passed in. Therefore, the value of size was thesame before and after the method call, making the output 3 and Option A the correctanswer.

40. B. Options A and D are equivalent and would allow the code to compile. They both areproper ways to access a static method from within an instance method. Option B isthe correct answer. The class would not compile because this.Drink has no meaningto the compiler. Finally, Option C would still allow the code to compile, even though itis considered a poor coding practice. While static members should be accessed in astatic way, it is not required.

41. C. The method signature requires one int value, followed by exactly one String,followed by String varargs, which can be an array of String values or zero or moreindividual String values. Only Option C conforms to these requirements, making itthe correct answer.

42. D. Option A is a statement about final static variables, not all static variables.Option B only applies to static variables marked private, not final. Option C is falsebecause static imports can be used to reference both variables and methods. OptionD is the correct answer because a static variable is accessible to all instances of theclass.

43. A. Option A is the correct answer because the first line of a constructor could bethis() or super(), making it an untrue statement. Option B is a true statementbecause the compiler will insert the default no-argument constructor if one is notdefined. Option C is also a true statement, since zero or more arguments may bepassed to the parent constructor, if the parent class defines such constructors. OptionD is also true. The value of a final instance variable should be set when it is declared,in an initialization block, or in a constructor.

44. D. The last static initialization block accesses height, which is an instance variable,not a static variable. Therefore, the code will not compile no matter how many finalmodifiers are removed, making Option D the correct answer. Note that if the lineheight = 4; was removed, then no final modifiers would need to be removed tomake the class compile.

45. D. Since a constructor call is not the first line of the RainForest() constructor, thecompiler inserts the no-argument super() call. Since the parent class, Forest, does notdefine a no-argument super() constructor, the RainForest() constructor does notcompile, and Option D is correct.

46. A. The code compiles without issue, so Option D is incorrect. In the main() method,the value 2 is first cast to a byte. It is then increased by one using the addition +operator. The addition + operator automatically promotes all byte and short values toint. Therefore, the value passed to the choose() in the main() method is an int. Thechoose(int) method is called, returning 5 and making Option A the correct answer.Note that without the addition operation in the main() method, byte would have beenused as the parameter to the choose() method, causing the choose(short) to beselected as the next closest type and outputting 2, making Option B the correct answer.

47. C. The variable startTime can be automatically converted to Integer by the compiler,but Integer is not a subclass of Long. Therefore, the code does not compile due thewrong variable type being passed to the getScore() method on line m2, and Option C iscorrect.

48. A. Java methods must start with a letter, the dollar $ symbol, or underscore _character. For these reasons, Options B and D are incorrect, and Option A is correct.Option C is incorrect. The hashtag (#) symbol cannot be included in a method name.

49. B. The protected modifier allows access by any subclass or class that is in the samepackage, therefore Option B is the correct answer.

50. D. A static import is used to import static members of another class. In this case,the withdrawal() and deposit() methods in the Bank class are not marked static.They require an instance of Bank to be used and cannot be imported as staticmethods. Therefore, Option D is correct. If the two methods in the Bank class weremarked static, then Option A would be the correct answer since wildcards can beused with static imports to import more than one method. Option B reverses thekeywords static and import, while Option C incorrectly imports a class, which cannotbe imported via a static import.

Chapter 7: Working with Inheritance1. C. The code does not compile, so Option A is incorrect. This code does not compile for

two reasons. First, the name variable is marked private in the Cinema class, whichmeans it cannot be accessed directly in the Movie class. Next, the Movie class defines aconstructor that is missing an explicit super() statement. Since Cinema does notinclude a no-argument constructor, the no-argument super() cannot be insertedautomatically by the compiler without a compilation error. For these two reasons, thecode does not compile, and Option C is the correct answer.

2. D. All abstract interface methods are implicitly public, making Option D the correctanswer. Option A is incorrect because protected conflicts with the implicit publicmodifier. Since static methods must have a body and abstract methods cannot havea body, Option B is incorrect. Finally, Option C is incorrect. A method, whether it be inan interface or a class, cannot be declared both final and abstract, as doing so wouldprevent it from ever being implemented.

3. C. A class cannot contain two methods with the same method signature, even if one isstatic and the other is not. Therefore, the code does not compile because the twodeclarations of playMusic() conflict with one another, making Option C the correctanswer.

4. A. Inheritance is often about improving code reusability, by allowing subclasses toinherit commonly used attributes and methods from parent classes, making Option Athe correct answer. Option B is incorrect. Inheritance can lead to either simpler ormore complex code, depending on how well it is structured. Option C is also incorrect.While all objects inherit methods from java.lang.Object, this does not apply toprimitives. Finally, Option D is incorrect because methods that reference themselvesare not a facet of inheritance.

5. A. Recall that this refers to an instance of the current class. Therefore, any superclassof Canine can be used as a return type of the method, including Canine itself, makingOption C an incorrect answer. Option B is also incorrect because Canine implementsthe Pet interface. An instance of a class can be assigned to any interface reference thatit inherits. Option D is incorrect because Object is the superclass of instances in Java.Finally, Option A is the correct answer. Canine cannot be returned as an instance ofClass because it does not inherit Class.

6. B. The key here is understanding which of these features of Java allow one developerto build their application around another developer’s code, even if that code is notready yet. For this problem, an interface is the best choice. If the two teams agree on acommon interface, one developer can write code that uses the interface, while anotherdeveloper writes code that implements the interface. Assuming neither team changesthe interface, the code can be easily integrated once both teams are done. For thesereasons, Option B is the correct answer.

7. B. The drive() method in the Car class does not override the version in the Automobile

class since the method is not visible to the Car class. Therefore, the final attribute inthe Automobile class does not prevent the Car class from implementing a method withthe same signature. The drive() method in the ElectricCar class is a valid override ofthe method in the Car class, with the access modifier expanding in the subclass. Forthese reasons, the code compiles, and Option D is incorrect. In the main() method, theobject created is an ElectricCar, even if it is assigned to a Car reference. Due topolymorphism, the method from the ElectricCar will be invoked, making Option Bthe correct answer.

8. D. While Java does not allow a class to extend more than one class, it does allow aclass to implement any number of interfaces. Multiple inheritance is, therefore, onlyallowed via interfaces, making Option D the correct answer.

9. C. There are three problems with this method override. First, the watch() method ismarked final in the Television class. The final modifier would have to be removedfrom the method definition in the Television class in order for the method to compilein the LCD class. Second, the return types void and Object are not covariant. One ofthem would have to be changed for the override to be compatible. Finally, the accessmodifier in the child class must be the same or broader than in the parent class. Sincepackage-private is narrower than protected, the code will not compile. For thesereasons, Option C is the correct answer.

10. C. First off, the return types of an overridden method must be covariant. Next, it istrue that the access modifier must be the same or broader in the child method. Using anarrower access modifier in the child class would not allow the code to compile.Overridden methods must not throw any new or broader checked exceptions than themethod in the superclass. For these reasons, Options A, B, and D are true statements.Option C is the false statement. An overridden method is not required to throw achecked exception defined in the parent class.

11. C. The process() method is declared final in the Computer class. The Laptop classthen attempts to override this method, resulting in a compilation error, makingOption C the correct answer.

12. A. The code compiles without issue, so Option D is incorrect. The rule for overriding amethod with exceptions is that the subclass cannot throw any new or broader checkedexceptions. Since FileNotFoundException is a subclass of IOException, it is considereda narrower exception, and therefore the overridden method is allowed. Due topolymorphism, the overridden version of the method in HighSchool is used, regardlessof the reference type, and 2 is printed, making Option A the correct answer. Note thatthe version of the method that takes the varargs is not used in this application.

13. B. Interface methods are implicitly public, making Option A and C incorrect. Interfacemethods can also not be declared final, whether they are static, default, or abstractmethods, making Option D incorrect. Option B is the correct answer because aninterface method can be declared static.

14. C. Having one class implement two interfaces that both define the same defaultmethod signature leads to a compiler error, unless the class overrides the defaultmethod. In this case, the Sprint class does override the walk() method correctly,therefore the code compiles without issue, and Option C is correct.

15. B. Interfaces can extend other interfaces, making Option A incorrect. On the otherhand, an interface cannot implement another interface, making Option B the correctanswer. A class can implement any number of interfaces, making Option C incorrect.Finally, a class can extend another class, making Option D incorrect.

16. D. The code does not compile because super.height is not visible in the Rocket class,making Option D the correct answer. Even though the Rocket class defines a heightvalue, the super keyword looks for an inherited version. Since there are none, the codedoes not compile. Note that super.getWeight() returns 3 from the variable in theparent class, as polymorphism and overriding does not apply to instance variables.

17. D. An abstract class can contain both abstract and concrete methods, while aninterface can only contain abstract methods. With Java 8, interfaces can now havestatic and default methods, but the question specifically excludes them, makingOption D the correct answer. Note that concrete classes cannot contain any abstractmethods.

18. C. The code does not compile, so Option D is incorrect. The IsoscelesRightTriangleclass is abstract; therefore, it cannot be instantiated on line g3. Only concrete classescan be instantiated, so the code does not compile, and Option C is the correct answer.The rest of the lines of code compile without issue. A concrete class can extend anabstract class, and an abstract class can extend a concrete class. Also, note that theoverride of getDescription() has a widening access modifier, which is fine per therules of overriding methods.

19. D. The play() method is overridden in Saxophone for both Horn and Woodwind, so thereturn type must be covariant with both. Unfortunately, the inherited methods mustalso be compatible with each other. Since Integer is not a subclass of Short, and viceversa, there is no subclass that can be used to fill in the blank that would allow thecode to compile. In other words, the Saxophone class cannot compile regardless of itsimplementation of play(), making Option D the correct answer.

20. C. A class can implement an interface, not extend it. Alternatively, a class extends anabstract class. Therefore, Option C is the correct answer.

21. A. The code compiles and runs without issue, making Options C and D incorrect.Although super.material and this.material are poor choices in accessing staticvariables, they are permitted. Since super is used to access the variable ingetMaterial(), the value papyrus is returned, making Option A the correct answer.Also, note that the constructor Book(String) is not used in the Encyclopedia class.

22. B. Options A and C are both true statements. Either the unknownBunny referencevariable is the same as the object type or it can be explicitly cast to the Bunny object

type, therefore giving it access to all its members. This is the key distinction betweenreference types and object types. Assigning a new reference does not change theunderlying object. Option D is also a true statement since any superclass that Bunnyextends or interface it implements could be used as the data type for unknownBunny.Option B is the false statement and the correct answer. An object can be assigned to areference variable type that it inherits, such as Object unknownBunny = new Bunny().

23. D. An abstract method cannot include the final or private method. If a classcontained either of these modifiers, then no concrete subclass would ever be able tooverride them with an implementation. For these reasons, Options A and B areincorrect. Option C is also incorrect because the default keyword applies to concreteinterface methods, not abstract methods. Finally, Option D is correct. The protected,package-private, and public access modifiers can each be applied to abstract methods.

24. D. The declaration of Sphere compiles without issue, so Option C is incorrect. The Marsclass declaration is invalid because Mars cannot extend Sphere, an interface, nor canMars implement Planet, a class. In other words, they are reversed. Since the code doesnot compile, Option D is the correct answer. Note that if Sphere and Planet wereswapped in the Mars class definition, the code would compile and the output would beMars, making Option A the correct answer.

25. B. A reference to a class can be implicitly assigned to a superclass reference without anexplicit class, making Option B the correct answer. Assigning a reference to a subclass,though, requires an explicit cast, making Option A incorrect. Option C is also incorrectbecause an interface does not inherit from a class. A reference to an interface requiresan explicit cast to be assigned to a reference of any class, even one that implementsthe interface. An interface reference requires an explicit cast to be assigned to a classreference. Finally, Option D is incorrect. An explicit cast is not required to assign areference to a class that implements an interface to a reference of the interface.

26. B. Interface variables are implicitly public, static, and final. Variables cannot bedeclared as abstract in interfaces, nor in classes.

27. C. The class is loaded first, with the static initialization block called and 1 isoutputted first. When the BlueCar is created in the main() method, the superclassinitialization happens first. The instance initialization blocks are executed before theconstructor, so 32 is outputted next. Finally, the class is loaded with the instanceinitialization blocks again being called before the constructor, outputting 45. Theresult is that 13245 is printed, making Option C the correct answer.

28. C. Overloaded methods share the same name but a different list of parameters and anoptionally different return type, while overridden methods share the exact same name,list of parameters, and return type. For both of these, the one commonality is that theyshare the same method name, making Option C the correct answer.

29. A. Although the casting is a bit much, the object in question is a SoccerBall. SinceSoccerBall extends Ball and implements Equipment, it can be explicitly cast to any of

those types, so no compilation error occurs. At runtime, the object is passed aroundand, due to polymorphism, can be read using any of those references since theunderlying object is a SoccerBall. In other words, casting it to a different referencevariable does not modify the object or cause it to lose its underlying SoccerBallinformation. Therefore, the code compiles without issue, and Option A is correct.

30. C. Both of these descriptions refer to variable and static method hiding, respectively,making Option C correct. Only instance methods can be overridden, making Options Aand B incorrect. Option D is also incorrect because replacing is not a real term in thiscontext.

31. B. The code does not compile, so Option D is incorrect. The issue here is that theoverride of getEqualSides() in Square is invalid. A static method cannot override anon-static method and vice versa. For this reason, Option B is the correct answer.

32. C. The application does not compile, but not for any reason having to do with the castin the main() method. The Rotorcraft class includes an abstract method, but the classitself is not marked abstract. Only interfaces and abstract classes can include abstractmethods. Since the code does not compile, Option C is the correct answer.

33. B. A class can trivially be assigned to a superclass reference variable but requires anexplicit cast to be assigned to a subclass reference variable. For these reasons, OptionB is correct.

34. C. A concrete class is the first non-abstract subclass that extends an abstract class andimplements any inherited interfaces. It is required to implement all inherited abstractmethods, making Option C the correct answer.

35. D. First of all, interfaces can only contain abstract, final, and default methods. Themethod fly() defined in CanFly is not marked static or default and defines animplementation, an empty {}, meaning it cannot be assumed to be abstract;therefore, the code does not compile. Next, the implementation of fly(int speed) inthe Bird class also does not compile, but not because of the signature. The methodbody fails to return an int value. Since it is an overloaded method, if it returned avalue it would compile without issue. Finally, the Eagle class does not compilebecause it extends the Bird class, which is marked final and therefore, cannot beextended. For these three reasons, Option D is the correct answer.

36. B. Abstract classes and interfaces can both contain static and abstract methods aswell as static variables, but only an interface can contain default methods.Therefore, Option B is correct.

37. C. Java does not allow multiple inheritance, so having one class extend two interfacesthat both define the same default method signature leads to a compiler error, unlessthe class overrides the method. In this case, though, the talk(String...) methoddefined in the Performance class is not an overridden version of method defined in theinterfaces because the signatures do not match. Therefore, the Performance class doesnot compile since the class inherits two default methods with the same signature and

no overridden version, making Option C the correct answer.

38. A. In Java, only non-static, non-final, and non-private methods are consideredvirtual and capable of being overridden in a subclass. For this reason, Option A is thecorrect answer.

39. B. An interface can only extend another interface, while a class can only extendanother class. A class can also implement an interface, although that comparison isnot part of the question text. Therefore, Option B is the correct answer.

40. A. The code compiles without issue, so Option D is incorrect. Java allows methods tobe overridden, but not variables. Therefore, marking them final does not preventthem from being reimplemented in a subclass. Furthermore, polymorphism does notapply in the same way it would to methods as it does to variables. In particular, thereference type determines the version of the secret variable that is selected, makingthe output 2 and Option A the correct answer.

41. D. Options A and C are incorrect because an overridden method cannot reduce thevisibility of the inherited method. Option B is incorrect because an overridden methodcannot declare a broader checked exception than the inherited method. Finally, OptionD is the correct answer. The removal of the checked exception, the application of abroader access modifier, and the addition of the final attribute are allowed foroverridden methods.

42. C. The setAnimal() method requires an object that is Dog or a subclass of Dog. SinceHusky extends Dog, Options A and B both allow the code to compile. Option D is alsovalid because a null value does not have a type and can be assigned to any referencevariable. Option C is the only value that prevents the code from compiling becauseWolf is not a subclass of Dog. Even though Wolf can be assigned to the instance Caninevariable, the setter requires a compatible parameter.

43. A. An interface method can be abstract and not have a body, or it can be default orstatic and have a body. An interface method cannot be final though, making OptionA the correct answer.

44. A. It looks like getSpace() in the Room class is an invalid override of the version in theHouse class since package-private is a more restrictive access modifier than protected,but the parameter list changes; therefore, this is an overloaded method, not anoverridden one. Furthermore, the Ballroom class is abstract so no object isinstantiated, but there is no requirement that an abstract class cannot contain arunnable main() method. For these reasons, the code compiles and runs without issue,making Option A correct.

45. D. Trick question! Option A seems like the correct answer, but the second part of thesentence is false, regardless of whether you insert overloaded or overridden.Overridden methods must have covariant return types, which may not be exactly thesame as the type in the parent class. Therefore, Option D is the correct answer.

46. B. If a parent class does not include a no-argument constructor, a child class can stillexplicitly declare one; it just has to call an appropriate parent constructor withsuper(), making Option A incorrect. If a parent class does not include a no-argumentconstructor, the child class must explicitly declare a constructor, since the compilerwill not be able to insert the default no-argument constructor, making Option Bcorrect. Option C is incorrect because a parent class can have a no-argumentconstructor, while its subclasses do not. If Option C was true, then all classes would berequired to have no-argument constructors since they all extend java.lang.Object,which has a no-argument constructor. Option D is also incorrect. The default no-argument constructor can be inserted into any class that directly extends a class thathas a no-argument constructor. Therefore, no constructors in the subclass arerequired.

47. D. The object type relates to the attributes of the object that exist in memory, whilethe reference type dictates how the object is able to be used by the caller. For thesereasons, Option D is correct.

48. A. The play() method is overridden in Violin for both MusicCreator andStringInstrument, so the return type must be covariant with both. Long is a subclass ofNumber, and therefore, it is covariant with the version in MusicCreator. Since itmatches the type in StringInstrument, it can be inserted into the blank and the codewould compile. While Integer is a subclass of Number, meaning the override forMusicCreator is valid, it is not a subclass of Long used in StringInstrument. Therefore,using Integer would cause the code to not compile. Finally, Number is compatible withthe version of the method in MusicCreator but not with the version inStringInstrument, because Number is a superclass of Long, not a subclass. For thesereasons, Long is the only class that allows the code to compile, making Option A thecorrect answer.

49. B. The primary motivation for adding default interface methods to Java was forbackward compatibility. These methods allow developers to update older classes witha newer version of an interface without breaking functionality in the existing classes,making Option B the correct answer. Option is A is nonsensical and not the correctanswer. Options C and D sound plausible, but both could be accomplished with staticinterface methods alone.

50. C. The rule for overriding a method with exceptions is that the subclass cannot throwany new or broader checked exceptions. Since IOException is a superclass ofEOFException, from the question description, we see that this is a broader exceptionand therefore not compatible. For this reason, the code does not compile, and OptionC is the correct answer.

Chapter 8: Handling Exceptions1. D. A try block must include either a catch or finally block, or both. The think()

method declares a try block but neither additional block. For this reason, the codedoes not compile, and Option D is the correct answer. The rest of the lines compilewithout issue, including k1.

2. B. The correct order of blocks is try, catch, and finally, making Option B the correctanswer.

3. D. Option D is the correct model. The class RuntimeException extends Exception, andboth Exception and Error extend Throwable. Finally, like all Java classes, they allinherit from Object. Notice that Error does not extend Exception, even though weoften refer to these generally as exceptions.

4. A. While Exception and RuntimeException are commonly caught in Java applications,it is recommended Error not be caught. An Error often indicates a failure of the JVMwhich cannot be recovered from. For this reason, Option A is correct, and Options Cand D are incorrect. Option B is not a class defined in the Java API; therefore, it is alsoincorrect.

5. D. The application does not compile because score is defined only within the tryblock. The other three places it is referenced, in the catch block, in the finally block,and outside the try-catch-finally block at the end, are not in scope for this variable andeach does not compile. Therefore, the correct answer is Option D.

6. B. ClassCastException, ArrayIndexOutOfBoundsException, andIllegalArgumentException are unchecked exceptions and can be thrown at any time.IOException is a checked exception that must be handled or declared when used,making Option B the correct answer.

7. A. The throws keyword is used in method declarations, while the throw keyword isused to throw an exception to the surrounding process, making Option A the correctanswer. The catch keyword is used to handle exceptions, not to create them or in thedeclaration of a method.

8. B. IOException is a subclass of Exception, so it must appear first in any related catchblocks. If Exception was to appear before IOException, then the IOException blockwould be considered unreachable code because any thrown IOException is alreadyhandled by the Exception catch block. For this reason, Option B is correct.

9. C. The application first enters the try block and outputs A. It then throws aRuntimeException, but the exception is not caught by the catch block sinceRuntimeException is not a subclass of ArrayIndexOutOfBoundsException (it is asuperclass). Next, the finally block is called and C is output. Finally, theRuntimeException is thrown by the main() method and a stack trace is printed. Forthese reasons, Option C is correct.

10. C. The application does not compile, so Option D is incorrect. The openDrawbridge()method compiles without issue, so Options A and B are incorrect. The issue here ishow the openDrawbridge() method is called from within the main() method on line p3.The openDrawbridge() method declares the checked exception, Exception, but themain() method from which it is called does not handle or declare the exception. Inorder for this code to compile, the main() method would have to have a try-catchstatement around line p3 that properly handles the checked exception, or the main()would have to be updated to declare a compatible checked exception. For thesereasons, line p3 does not compile, and Option C is the correct answer.

11. B. NullPointerException and ArithmeticException both extend RuntimeException,which are unchecked exceptions and not required to be handled or declared in themethod in which they are thrown. On the other hand, Exception is a checkedexception and must be handled or declared by the method in which it is thrown.Therefore, Option B is the correct answer.

12. A. The code compiles and runs without issues, so Options C and D are incorrect. Thetry block throws a ClassCastException. Since ClassCastException is not a subclass ofArrayIndexOutOfBoundsException, the first catch block is skipped. For the secondcatch block, ClassCastException is a subclass of Throwable, so that block is executed.Afterward, the finally block is executed and then control returns to the main()method with no exception being thrown. The result is that 1345 is printed, makingOption A the correct answer.

13. C. A finally block can throw an exception, in which case not every line of the finallyblock would be executed. For this reason, Options A and D are incorrect. Option B isalso incorrect The finally block is called regardless of whether or not the relatedcatch block is executed. Option C is the correct answer. Unlike an if-then statement,which can take a single statement, a finally statement requires brackets {}.

14. C. The code does not compile because the catch blocks are used in the wrong order.Since IOException is a superclass of FileNotFoundException, theFileNotFoundException is considered unreachable code. For this reason, the code doesnot compile, and Option C is correct.

15. C. A try statement requires a catch or a finally block. Without one of them, the codewill not compile; therefore, Option D is incorrect. A try statement can also be usedwith both a catch and finally block, making Option C the correct answer. Note thatfinalize is not a keyword, but a method inherited from java.lang.Object.

16. B. Option A is a true statement about exceptions and when they are often applied.Option B is the false statement and the correct answer. An application that throws anexception can choose to handle the exception and avoid termination. Option C is also atrue statement. For example, a NullPointerException can be avoided on a null objectby testing whether or not the object is null before attempting to use it. Option D isalso a correct statement. Attempting to recover from unexpected problems is animportant aspect of proper exception handling.

17. D. The code does not compile because the catch block uses parentheses () instead ofbrackets {}, making Option D the correct answer. Note that Boat does not extendTransport, so while the override on line j1 appears to be invalid since Exception is abroader checked exception than CapsizedException, that code compiles without issue.If the catch block was fixed, the code would output 4, making Option A the correctanswer.

18. B. Overridden methods cannot throw new or broader checked exceptions than the onethey inherit. Since Exception is a broader checked exception than PrintException,Option B is not allowed and is the correct choice. Alternatively, declaring narrower orthe same checked exceptions or removing them entirely is allowed, making Options Aand C incorrect. Since Option B is correct, Option D is incorrect.

19. D. All three of those classes belong to the java.lang package, so Option C seems likethe correct answer. The Java compiler, though, includes java.lang by default, so noimport statement is actually required to use those three classes, making Option D thecorrect answer.

20. C. The code does not compile because the catch block is missing a variable type andname, such as catch (Exception e) . Therefore, Option C is the correct answer. Bothimplementations of getSymbol() compile without issue, including the overriddenmethod. A subclass can swallow a checked exception for a method declared in a parentclass; it just cannot declare any new or broader checked exceptions.

21. B. Checked exceptions must be handled or declared or the program will not compile,while unchecked exceptions can be optionally handled. On the other hand,java.lang.Error should never be handled by the application because it often indicatesan unrecoverable state in the JVM, such as running out of memory. For these reasons,Option B is the correct answer.

22. B. The application does not compile, so Option D is incorrect. The checkedKnightAttackingException thrown in the try block is handled by the associated catchblock. The ClassCastException is an unchecked exception, so it is not required to behandled or declared and line q1 compiles without issue. The finally block throws achecked CastleUnderSiegeException, which is required to be handled or declared bythe method, but is not. There is no try-catch around line q2, and the method does notdeclare a compatible checked exception, only an unchecked exception. For this reason,line q2 does not compile, and Option B is the correct answer. Lastly, line q3 compileswithout issue because the unchecked RuntimeException is not required to be handledor declared by the call in the main() method.

23. A. If an exception matches multiple catch blocks, the first one that it encounters willbe the only one executed, making Option A correct, and Options B and C incorrect.Option D is also incorrect. It is possible to write two consecutive catch blocks that cancatch the same exception, with the first type being a subclass of the second. In thisscenario, an exception thrown of the first type would match both catch blocks, butonly the first catch block would be executed, since it is the more specific match.

24. C. The code does not compile due to the call to compute() in the main() method. Eventhough the compute() method only throws an unchecked exception, its methoddeclaration includes the Exception class, which is a checked exception. For thisreason, the checked exception must be handled or declared in the main() method inwhich it is called. While there is a try-catch block in the main() method, it is only forthe unchecked NullPointerException. Since Exception is not a subclass ofNullPointerException, the checked Exception is not properly handled or declared andthe code does not compile, making Option C the correct answer.

25. D. A NullPointerException can be thrown if the value of list is null. Likewise, anArrayIndexOutOfBoundsException can be thrown if the value of list is an array withfewer than 10 elements. Finally, a ClassCastException can be thrown if list isassigned an object that is not of type Boolean[]. For example, the assignment list =(Boolean[]) new Object() will compile without issue but throws aClassCastException at runtime. Therefore, the first three options are possible, makingOption D the correct answer.

26. B. A StackOverflowError occurs when a program recurses too deeply into an infiniteloop. It is considered an error because the JVM often runs out of memory and cannotrecover. A NullPointerException occurs when an instance method or variable on anull reference is used. For these reasons, Option B is correct. A NoClassDefFoundErroroccurs when code available at compile time is not available at runtime. AClassCastException occurs when an object is cast to an incompatible reference type.Finally, an IllegalArgumentException occurs when invalid parameters are sent to amethod.

27. C. Checked exceptions are commonly used to force a caller to deal with an expectedtype of problem, such as the inability to write a file to the file system. Without dealingwith all checked exceptions thrown by the method, the calling code does not compile,so Option A is a true statement. Option B is also a true statement. Declaring variousdifferent exceptions informs the caller of the potential types of problems the methodcan encounter. Option C is the correct answer. There may be no recourse in handlingan exception other than to terminate the application. Finally, Option D is also a truestatement because it gives the caller a chance to recover from an exception, such aswriting file data to a backup location.

28. D. This code does not compile because the catch and finally blocks are in the wrongorder, making Option D the correct answer. If the order was flipped, the output wouldbe Finished!Joyce Hopper, making Option B correct.

29. A. A try statement is not required to have a finally block, but if it does, there can beat most one. Furthermore, a try statement can have any number of catch blocks ornone at all. For these reasons, Option A is the correct answer.

30. D. The code compiles without issue, so Option C is incorrect. The key here is noticingthat count, an instance variable, is initialized with a value of 0. The getDuckies()method ends up computing 5/0, which leads to an unchecked ArithmeticException at

runtime, making Option D the correct answer.

31. B. If both the catch and finally blocks throw an exception, the one from the finallyblock is propagated to the caller, with the one from the catch block being dropped,making Option B the correct answer. Note that Option C is incorrect due to the factthat only one exception can be thrown to the caller.

32. A. The application does not compile because the roar() method in the BigCat classuses throw instead of throws, making Option A the correct answer. Note that if thecorrect keyword was used, the code would compile without issues, and Option Dwould be correct. Also the override of roar() in the Lion class is valid, since theoverridden method has a broader access modifier and does not declare any new orbroader checked exceptions.

33. A. Although this code uses the RuntimeException and Exception classes, the questionis about casting. Exception is not a subclass of RuntimeException, so the assignmenton the second line throws a ClassCastException at runtime, making Option A correct.

34. C. All exceptions in Java inherit from Throwable, making Option C the correct answer.Note that Error and Exception extend Throwable, and RuntimeException extendsException.

35. B. If both values are valid non-null String objects, then no exception will be thrown,with the statement in the finally block being executed first, before returning controlto the main() method; therefore, the second statement is a possible output. If eithervalue is null, then the toString() method will cause a NullPointerException to bethrown. In both cases, the finally block will execute first, printing Posted:, even ifthere is an exception. For this reason, the first statement is not a possible output, andOption B is correct.

36. A. ClassCastException is a subclass of RuntimeException, so it must appear first in anyrelated catch blocks. If RuntimeException was to appear before ClassCastException,then the ClassCastException block would be considered unreachable code, since anythrown ClassCastException is already handled by the RuntimeException catch block.For this reason, Option A is correct.

37. C. Option A is incorrect. You should probably seek help if the computer is on fire!Option B is incorrect because code that does not compile cannot run and thereforecannot throw any exceptions. Option C is the best answer, since anIllegalArgumentException can be used to alert a caller of missing or invalid data.Option D is incorrect; finishing sooner is rarely considered a problem.

38. C. The code does not compile due to an invalid override of the operate() method. Anoverridden method must not throw any new or broader checked exceptions than themethod it inherits. Even though RuntimeException is a subclass of Exception,Exception is considered a new checked exception, since RuntimeException is anunchecked exception. Therefore, the code does not compile, and Option C is correct.

39. D. A NullPointerException is an unchecked exception. While it can be handled by thesurrounding method, either through a try-catch block or included in the methoddeclaration, these are optional. For this reason, Option D is correct.

40. D. In this application, the throw RuntimeException(String) statement in the zipper()method does not include the new keyword. The new keyword is required to create theobject being thrown, since RuntimeException(String) is a constructor. For this reason,the code does not compile, and Option D is correct. If the keyword new was insertedproperly, then the try block would throw a CastClassException, which would bereplaced with a RuntimeException to the calling method by the catch block. The catchblock in the main() method would then be activated, and no output would be printed,making Option C correct.

41. C. For this question, notice that all the exceptions thrown or caught are uncheckedexceptions. First, the ClassCastException is thrown in the try block and caught by thesecond catch block since it inherits from RuntimeException, notIllegalArgumentException. Next, a NullPointerException is thrown, but before it canbe returned the finally block is executed and a RuntimeException replaces it. Theapplication exits and the caller sees the RuntimeException in the stack trace, makingOption C the correct answer. If the finally block did not throw any exceptions, thenOption B would be the correct answer.

42. D. Trick question! Options A, B, and C are each invalid overrides of the methodbecause the return type must be covariant with void. For this reason, Option D is thecorrect answer. If the return types were changed to be void, then Option A would be avalid override. Options B and C would still be incorrect, since overridden methodscannot throw broader checked exceptions than the inherited method.

43. D. The code does not compile because the catch block is missing a variable name, suchas catch (Error e). Therefore, Option D is the correct answer. If a variable name wasadded, the application would produce a stack trace at runtime and Option C would bethe correct answer. Because IllegalArgumentException does not inherit from Error,the catch block would be skipped and the exception sent to the main() method atruntime. Note that the declaration of RuntimeException by both methods isunnecessary since it is unchecked, although allowed by the compiler.

44. D. The openDrawbridge() is capable of throwing a variety of exceptions, includingchecked Exception and DragonException as well as an unchecked RuntimeException.All of these are handled by the fact that the method declares the checked Exceptionclass in the method signature, which all the exceptions within the class inherit. Forthis reason, the openDrawbridge() method compiles without issue. The call toopenDrawbridge() in the main() method also compiles without issue because themain() method declares Exception in its signature. For these reasons, the codecompiles but a stack trace is printed at runtime, making Option D the correct answer.In case you are wondering, the caller would see RuntimeException: Or maybe thisone in the stack trace at runtime, since the exception in the finally block replaces the

one from the try block. Note that the exception in the catch block is never reachedbecause the RuntimeException type declared in the catch block does not handleException.

45. C. Both IllegalArgumentException and ClassCastException inherit RuntimeException,but neither is a subclass of the other. For this reason, they can be listed in eitherorder, making Option C the correct statement.

46. D. The class RuntimeException is not an interface and it cannot be implemented. Forthis reason, the Problem class does not compile, and Option D is the correct answer.Note that this is the only compilation problem in the application. If implements waschanged to extends, the code would compile and Problem?Fixed! would be printed,making Option A the correct answer.

47. D. The question is designed to see how closely you pay attention to throw and throws!The try block uses the incorrect keyword, throws, to create an exception. For thisreason, the code does not compile, and Option D is correct. If throws was changed tothrow, then the code would compile without issue, and Option B would be correct.

48. D. A Java application tends to only throw an Error when the application has entered afinal, unrecoverable state. Options A and C are incorrect. These types of errors arecommon and expected in most software applications, and should not cause theapplication to terminate. Option B uses the word temporarily, meaning the networkconnection will come back. In this case, a regular exception could be used to try torecover from this state. Option D is the correct answer because running out ofmemory is usually unrecoverable in Java.

49. C. While a catch block is permitted to include an embedded try-catch block, the issuehere is that the variable name e is already used by the first catch block. In the secondcatch block, it is equivalent to declaring a variable e twice. For this reason, line z1 doesnot compile, and Option C is the correct answer. If a different variable name was usedfor either catch block, then the code would compile without issue, and Option A wouldbe the correct answer.

50. B. The finally block of the snore() method throws a new checked exception on linex1, but there is no try-catch block around it to handle it, nor does the snore() methoddeclare any checked exceptions. For these reasons, line x1 does not compile, andOption B is the correct answer. The rest of the lines of code compile without issue,even line x3 where a static method is being accessed using an instance reference.Note that the code inside the try block, if it ran, would produce anArrayIndexOutOfBoundsException, which would be caught by the RuntimeExceptioncatch block, printing Awake!. What happens next would depend on how the finallyblock was corrected.

Chapter 9: Working with Selected Classes from the JavaAPI1. C. Option A is incorrect because StringBuilder does not support multiple threads. In

fact, threads aren’t even covered on the OCA, which should be your clue that thisanswer is wrong! You don’t need to know this for the exam, but StringBuffer supportsmultiple threads. Option B is incorrect because == compares references, not values.Option D is incorrect because both String and StringBuilder support languages andencodings. Option C is correct and the primary reason to use StringBuilder. Stringoften creates a new object each time you call certain methods on the object likeconcat(). StringBuilder optimizes operations like append() because it is mutable.

2. D. A String can be created using a literal rather than calling a constructor directly,making Option A incorrect. A string pool exists for String reuse, making Option Bincorrect. A String is final and immutable, making Option C incorrect and Option Dcorrect.

3. D. This question is testing whether you understand how method chaining works.Option A creates an empty StringBuilder and then adds the five characters in clown toit. Option B simply creates the clown when calling the constructor. Finally, Option Ccreates the same value, just in two parts. Therefore, Option D is correct.

4. B. Since StringBuilder is mutable, each call to append adds to the value. When callingprint, toString() is automatically called and 333 806 1601 is output. Therefore,Option B is correct.

5. B. List is an interface and not a class. It cannot be instantiated. While Object is aconcrete class, it does not implement the List interface so it cannot be assigned tofrisbees. Note that if you were to add an explicit cast, it would compile and throw anexception at runtime. Of the three options, only ArrayList can fill in the blank, soOption B is correct.

6. C. An ArrayList does not automatically sort the elements. It simply remembers themin order. Since Java uses zero-based indexes, Option C is correct.

7. C. Calling the constructor and then insert() is an example of method chaining.However, the sb.length() call is a problem. The sb reference doesn’t exist until afterthe chained calls complete. Just because it happens to be on a separate line doesn’tchange when the reference is created. Since the code does not compile, Option C iscorrect.

8. A. While the ArrayList is declared with an initial capacity of one element, it is free toexpand as more elements are added. Each of the three calls to the add() method addsan element to the end of the ArrayList. The remove() method call deletes the elementat index 2, which is Art. Therefore, Option A is correct.

9. C. On line 12, the value of the StringBuilder is 12. On line 13, it becomes 123. Since

StringBuilder is mutable, storing the result in the same reference is redundant. Thenon line 14, the value is reversed, giving us 321 and making Option C correct.

10. D. Option A is incorrect as it describes autoboxing. Options B and C are not possible inJava. Option D is correct as it describes lambdas. Lambdas use deferred execution andcan be run elsewhere in the codebase.

11. D. A StringBuilder is mutable, so the length is two after line 6 completes. TheStringBuilder methods return a reference to the same object so you can chainmethod calls. Therefore, line and anotherLine refer to the same object. This meansthat line 7 prints true. Then on line 9, both references point to the same object oflength 2, and Option D is correct.

12. D. The add() and get() methods are available on ArrayList. However, ArrayList usessize rather than length to get the number of elements. Therefore, Option D is correct.If length was changed to size, Option B would compile if put in the blank. Option Astill wouldn’t compile in the blank because a cast would be needed to store the valuein str.

13. D. Option A is tricky, but incorrect. While a lambda can have zero parameters, aPredicate cannot. A Predicate is defined as a type mapping to a boolean. Option B isclearly incorrect as -> separates the parts of a lambda. Options C and D are similar.Option C is incorrect because return is only allowed when the brackets are present.Option D is correct.

14. A. Lines 20–22 create an ArrayList with two elements. Line 23 replaces the secondone with a new value. Now chars is [a, c]. Then line 24 removes the first element,making it just [c]. Option A is correct because there is only one element, but it is notthe value b.

15. D. Trick question. There is no reverse method on the String class. There is one on theStringBuilder class. Therefore, the code does not compile, and Option D is correct.

16. A. When creating a lambda with only one parameter, there are a few variants. Thepred1 approach shows the shortest way, where the type is omitted and the parenthesesare omitted. The pred2 approach is similar except it includes the parentheses. Both arelegal. The pred4 approach is the long way with both the parentheses and typespecified. The only one that doesn’t compile is pred3. The parentheses are required ifincluding the type.

17. A. This is a correct example of code that uses a lambda. The interface has a singleabstract method. The lambda correctly takes one double parameter and returns aboolean. This matches the interface. The lambda syntax is correct. Since 45 is greaterthan 5, Option A is correct.

18. A. Since String is immutable, each call to concat() returns a new object with the newvalue. However, that return value is ignored and the teams variable never changes invalue. Therefore it stays as 694, and Option A is correct.

19. A. The ArrayList class is in the java.util package, making I correct. The LocalDateclass is in the java.time package, making II incorrect. The String class is in thejava.lang package, which means you can use it without typing an import, making IIIincorrect. Therefore, Option A is correct.

20. C. Option A is straightforward and outputs radical robots. Option B does the same ina convoluted manner. First Option B removes all the characters after the first one. Itdoesn’t matter that there aren’t actually 100 characters to delete. Then it appendsobots to the end, making the builder contain robots. Finally, it inserts the remainderof the string immediately after the first index. Try drawing the flow if this is hard toenvision. Option D also creates the same value by inserting robots immediately afterthe end of the StringBuilder. Option C is close, but it has an off-by-one error. Itinserts robots after the letter l rather than after the space. This results in the valueradicalrobots followed by a space. Option C is different than the others and thecorrect answer.

21. A. Since we are creating the list from an array, it is a fixed size. We are allowed tochange elements. At the end of this code, museums is [Art, Science]. Therefore, itcontains Art, and Option A is correct.

22. D. Options A and B are not true if the String is "deabc". Option C is not true if theString is "abcde". Option D is true in all cases.

23. D. Line 25 does not compile. On an ArrayList, the method to get the number ofelements is size. The length() method is used for a String or StringBuilder.

24. B. The toString() method call doesn’t help in narrowing things down as all Javaobjects have that method available. The other two methods are more helpful. String isthe only type of these three to have a startsWith() method, making Option B correct.String also has the replace() method declared here. If you memorized the whole API,you might know that StringBuilder also has a replace() method, but it requires threeparameters instead of two. Please don’t memorize the API in that level of detail. Weincluded what you need to know in our study guide. If you do have this outsideknowledge, be careful not to read into the questions!

25. B. The <> is known as the diamond operator. Here, it works as a shortcut to avoidrepeating the generic type twice for the same declaration. On the right side of theexpression, this is a handy shortcut. Java still needs the type on the left side so there issomething to infer. In the figure, position P is the left side and position Q is the rightside. Therefore, Option B is correct.

26. D. The type in the lambda must match the generic declared on the Predicate. In thiscase, that is String. Therefore, Options A and B are incorrect. While Option C is of thecorrect type, it uses the variable s, which is already in use from the main() methodparameter. Therefore, none of these are correct, and Option D is the answer.

27. A. A String is immutable so a different object is returned on line 6. The objectanotherLine points to is of length 2 after line 6 completes. However, the original line

reference still points to an object of length 1. Therefore, Option A is correct.

28. C. While it is common for a Predicate to have a generic type, it is not required.However, it is treated like a Predicate of type Object if the generic type is missing.Since startsWith() does not exist on Object, the first line does not compile, andOption C is correct.

29. B. LocalDate only includes the date portion and not the time portion. There is no classnamed LocalTimeStamp. The other two, LocalDateTime and LocalTime, both include thetime elements, making Option B correct.

30. D. Line 4 creates a String of length 5. Since String is immutable, line 5 creates a newString with the value 1 and assigns it to builder. Remember that indexes in Javabegin with 0, so the substring() method is taking the values from the fifth elementthrough the end. Since the first element is the last element, there’s only one characterin there. Then line 6 tries to retrieve the second indexed element. Since there is onlyone element, this gives a StringIndexOutOfBoundsException, and Option D is correct.

31. D. When you’re using brackets, both the return keyword and semicolon are needed forthe lambda to compile, making Option D correct.

32. B. Java 8 date and time classes are immutable. The plusDays method returns aLocalDate object presenting Christmas Eve (December 24th). However, this returnvalue is ignored. The xmas variable still represents the original value, so Option B iscorrect.

33. A. Line 3 creates an empty StringBuilder. Line 4 adds three characters to it. Line 5removes the first character, resulting in ed. Line 6 deletes the characters starting atposition 1 and ending right before position 2, which removes the character at index 1,which is d. The only character left is e, so Option A is correct.

34. B. While it is common for a Predicate to have a generic type, it is not required. Whenthe generic is omitted, it is treated like a Predicate of type Object. Since the equals()method exists on Object, this is fine. Option B is correct because the Predicate testsas false.

35. C. In Java, most things use zero-based indexes, including arrays and a String. Monthsare an exception to this convention starting Java 8. This makes the answer eitherOption C or D. However, LocalTime does not contain date fields, so it has to be OptionC.

36. C. Predicate is an interface with one method. The method signature is boolean test(Tt). Option C is the answer because the method accepts one parameter rather than two.

37. B. Be careful here. The Period class uses a static helper method to return the period.It does not chain method calls, so period1 only represents three days. Since three daysis less than 10 days, period2 is larger, and Option B is correct.

38. B. The code starts by correctly creating a date representing January 1, 2017, and a

period representing one day. It then explicitly defines the format as month followed byday followed by year. Finally, the code subtracts a day, giving us the formatted versionof December 31, 2016.

39. C. The trim() method returns a String with all leading and trailing white spaceremoved. In this question, that’s the seven-character String: ":) - (:". Options A andB are incorrect because they do not remove the first blank space in happy. Option D isincorrect because it does not remove the last character in happy. Therefore, Option C iscorrect.

40. C. The Period class creates immutable objects and is usually used to add/subtractfrom a LocalDate or LocalDateTime object. It allows creating date, week, month, oryear periods. Since it cannot be used for time, Option C is the answer.

41. D. Line 4 creates a StringBuilder of length 5. Pay attention to the substring()method StringBuilder. It returns a String with the value 321. It does not change theStringBuilder itself. Then line 6 is retrieving the second indexed element from thatunchanged value, which is 4. Therefore, Option D is correct.

42. B. This one is tricky. There are two remove() methods available on ArrayList. Oneremoves an element by index and takes an int parameter. The other removes anelement by value. Due to the generics, it takes an Integer parameter in this example.Since the int primitive is a better match, the element with index 2 is removed, whichis the value of 1. Therefore, Option B is correct.

43. C. ArrayList has a size() method rather than a length() method, making Option Aincorrect. The charAt() and length() methods are declared on both String andStringBuilder. However, the insert() method is only declared on a StringBuilderand not a String. Therefore, Option C is correct.

44. C. The minusNanos and plusNanos are the smallest units available, making Option Ccorrect. Option D is incorrect because LocalTime is not that granular. Note that whileyou can add milliseconds by adding many nanoseconds, there isn’t a method for it. Amillisecond is also larger than a nanosecond. Finally, don’t be tricked by the fact thatLocalTime is immutable. You can still add time; it just gets returned as a differentobject.

45. D. When creating a formatter object, remember that MM represents month while mmrepresents minute. Since there are not minutes defined on a LocalDate object, thecode throws an UnsupportedTemporalTypeException. You don’t need to know the nameof the exception, but you do need to know that an exception is thrown.

46. D. There are two signatures for the replace() method. One takes two char parameters.The other signature takes a CharSequence. Both String and StringBuilder implementthis interface. This makes all three alternatives correct, and Option D is correct.

47. C. Pay attention to the data types. The print() method is looping through a list ofString objects. However, the Predicate expects an Integer. Since these don’t match,

the if statement does not compile.

48. D. Line 12 creates an empty ArrayList. While it isn’t recommended to use generics ononly the left side of the assignment operator, this is allowed. It just gives a warning.Lines 13 and 14 add two elements. Line 15 resets to an empty ArrayList. Line 16 addsan element, so now we have an ArrayList of size 1. Line 17 attempts to remove theelement at index 1. Since Java uses zero-based indexes, there isn’t an element thereand the code throws an IndexOutOfBoundsException.

49. C. The declaration of witch is incorrect. It tries to store a char into a String variablereference. This does not compile, making Option C correct. If this was fixed, theanswer would be Option B.

50. C. The Java 8 date and time classes are immutable. This means they do not containsetter methods and the code does not compile.

Chapter 10: OCA Practice Exam1. E. The first time through the loop, we are calling indexOf on an empty StringBuilder.

This returns -1. Since we cannot insert at index -1, the code throws aStringIndexOutOfBoundsException.

2. C, E. In Option A, the assignment operator = incorrectly comes after the addition +operator. In Option B, the addition operator + incorrectly comes after the division /operator. In Option D, the subtraction operator - incorrectly comes after themultiplication * operator. This leaves Options C and E as the correct answers. Forthese answers, it may help to remember that the modulus operator %, multiplicationoperator *, and division operator / have the same operator precedence.

3. B, C, F. Option A is incorrect because a getter should not take a value. Option D isincorrect because the prefix is should only be with boolean values. Option E isincorrect because gimme is not a valid JavaBean prefix. Options B, C, and F are eachproper JavaBean method signatures.

4. A, E. Line 24 does not compile because arrays use length. It is ArrayList that usessize(). All of the other lines compile, making Option A correct. It is allowed to split upthe braces in the 2D array declaration on line 20. The code is also allowed to usecrossword.length as the loop condition on line 22, although this is not a good idea.The array starts out with all 200 of the cells initialized to the default value for an intof 0. Both loops iterate starting at 0 and stopping before 10, which causes only half ofthe array to be set to 'x'. The other half still has the initial default value of 0, makingOption E correct.

5. B, D. Options A and E are incorrect because they indicate states that the applicationcan possibly recover from. An Error generally indicates an unrecoverable problem.While it is possible to catch an Error, it is strongly recommended that an applicationnever do so, making Options B and D correct. Finally, Option C is incorrect becauseError extends from Throwable, not Exception, and is unchecked.

6. A, C, D. The first import statement allows only the class forest.Bird to be available,making Option A correct and Options E and F incorrect. Option B is incorrect since thethird import statement only allows access to classes within the savana package, notany sub-packages. Option C is correct because the second import statement allows anyclass in the jungle.tree package to be accessible. Finally, Option D is correct becausejava.lang.* is implicitly included in all Java classes.

7. C. Mutable means the object can change state. Immutable means the object cannotchange state. An ArrayList stores a collection of objects. It mutates as the elementschange. A StringBuilder is also mutable as it improves performance by not creating anew object each time it changes. A String is immutable. Methods that look like theychange the value simply return a different String object. The date/time objects addedin Java 8, such as LocalDateTime, are also immutable. Therefore, Option C is correctwith String and LocalDateTime as the immutable object types.

8. C. On the first iteration through the loop, the first five characters are removed andbuilder becomes s growing. Since there are more than five characters left, the loopiterates again. This time, five more characters are removed and builder becomes wing.This matches Option C.

9. D. The code compiles without issue, so Option E is incorrect. The key here is that noneof the variables are assigned the same object due to the use of the new keyword.Comparing any two variables with == will always result in an evaluation of false,making the first two values of the print statement be false and false. On the otherhand, they all have an underlying String value equivalent to up, so calling equals() onany two variables will return true. Option D is the correct answer that matches whatthe application will print.

10. C. Lines 4 and 5 both print false since a String should be compared with a methodrather than ==, especially when not comparing two values from the string pool. Line 6also prints false because one value is uppercase and the other is lowercase. Line 7prints true because both values are uppercase. Lines 8 and 9 print true because theydon’t look at the case. This makes Option C the answer.

11. A, B, C. Let’s look at each one in turn. Option A is correct because the labels are notreferenced. Option B is correct because the outer while is broader than the innerwhile. Since there is no other code in the loop, it is not needed. Option C is also correctbecause a label is not used. Option D is incorrect because the inner loop is morespecific than the outer loop. While the code still compiles, it prints one less chapter.Options E and F are incorrect because you cannot remove one half of a loop constructand have it compile.

12. B, C. A long cannot contain a number with decimal points, preventing Options B and Cfrom compiling. Options D and E show you can force a number to be a long by endingit with an upper- or lowercase L. This does not work if the number has a decimal point.Option F shows how to use underscores to break up a number.

13. A. A while loop checks the condition before executing. Since the hour is not less thanone, the loop never enters, and Option A is correct. This is good, because we’d have aninfinite loop if the loop was entered since the result of plusHours is ignored.

14. D. This question appears to ask you about involved array logic. Instead, it is checkingto see if you remember that instance and class variables are initialized to null. Line 6throws a NullPointerException. If the array was declared, the answer would be Ebecause the code would throw an ArrayStoreException on line 8.

15. C, E. The diamond operator is only allowed to be used when instantiating rather thandeclaring. In other words, it can’t go on the left side of the equal sign. Therefore,Options B, D, and F are incorrect. The remaining three options compile. However,Option A produces a warning because generics are not used on the right side of theassignment operator. Therefore, Options C and E are correct. Option C is better thanOption E since it uses the diamond operator rather than specifying a redundant type.

16. B, D. At the end of the method, shoe1 and shoe3 both point to "flip flop". shoe2points to "croc". Since there are no references to "sandal", it is eligible for garbagecollection, making Option B correct. However, garage collection is not guaranteed torun, so Option D is also correct.

17. C. The code does not compile, so Options A and B are incorrect. The getFish() methodis declared properly in the Fish class and successfully overridden in the Clownfishclass. An overridden method must not declare any new or broader checked exceptions,but it is allowed to declare narrower exceptions or drop checked exceptions. Theoverridden method also uses a covariant return type. The use of final on the methodand class declarations has no meaningful impact, since the methods and classes arenot extended in this application. So where does the compilation error occur? In themain() method! Even though the Clownfish version of getFish() does not declare achecked exception, the call f.getFish() uses a Fish reference variable. Since the Fishreference variable is used and that version of the method declares a checkedException, the compiler enforces that the checked exception must be handled by themain() method. Since this checked exception is not handled with a try-catch block norby the main() method declaration, the code does not compile, and Option C is thecorrect answer.

18. A. This is a correct example of using lambdas. The code creates an ArrayList withthree elements. The print() method loops through and checks for negative numbers.Option A is correct.

19. F. A try statement requires a catch or a finally block. It can also have both a catchand a finally block. Since no option matches these rules, Option F is the correctanswer. Note that finalize is not a keyword but a method inherited fromjava.lang.Object. Lastly, the throws keyword can be applied to method declarationsand is not used as part of a try statement.

20. A. On line 12, result is first set to 8. On line 13, the boolean condition is true because8 > 7. On line 13, result is incremented to 9. Then the inner loop runs, decrementingresult until it is no longer greater than 5. On line 18, loop execution is completedbecause result is equal to 5. The break statement says to skip to after the labeled loop,which is line 20. Then result is printed as 5, making Option A correct.

21. C. The code compiles and runs without exception, making Options E and F incorrect.The question is testing your knowledge of variable scope. The teeth variable is staticin the Alligator class, meaning the same value is accessible from all instances of theclass, including the static main() method. The static variable teeth is incrementedeach time the constructor is called. Since teeth is a local variable within the snap()method, the argument value is used, but changes to the local variable do not affect thestatic variable teeth. Since the local variable teeth is not used after it isdecremented, the decrement operation has no meaningful effect on the program flowor the static variable teeth. Since the constructor is called twice, with snap()executed after each constructor call, the output printed is 1 2, making Option C the

correct answer.

22. A. A String is immutable. Since the result of the concat() method call is ignored, thevalue of witch never changes. It stays as a single letter, and Option A is correct.

23. A, C, F. An interface method is exactly one of three types: default, static, or abstract.For this reason, Options A, C, and F are correct. An interface method cannot beprotected nor private because the access modifier is always public, even when notspecified, making Options B and D incorrect. Option E is also incorrect because finalcannot be applied to static methods, since they cannot be overridden. It can also notbe applied to default and abstract methods because they are always able to beoverridden.

24. D. Look at the loop condition carefully. It tries to assign null to a String variable. Thisis not an expression that returns a boolean. Therefore, the code does not compile, andOption D is correct. If this was fixed by making the loop condition tie == null, thenOption B would be correct.

25. B, F. A class may be defined without a package statement, making the class part of thedefault package. For this reason, Options A and D are incorrect. Every Java classimplicitly imports exactly one package, java.lang.*, making Option B correct andOption C incorrect. Option E is incorrect because an import statement is not required.Finally, Option F is correct; any class that does not extend another class implicitlyextends java.lang.Object.

26. D. A class cannot inherit two interfaces that declare the same default method, unlessthe class overrides them. In this case, the version of grow() in the Tree class is anoverloaded method, not an overridden one. Therefore, the code does not compile dueto the declaration of Tree on line m1, and Option D is the correct answer.

27. D. Variables are allowed to start with an underscore and are allowed to contain a $.Therefore, all the variable declarations compile, making Options A, B, and C incorrect.However, the println() refers to the uninitialized local boolean. Since local variablesare not automatically initialized, the code does not compile, and Option D is correct.

28. A. Prefix operators, such as ––x and ++x, modify the variable and evaluate to the newvalue, while postfix operators, such as x–– and x++, modify the variable but return theoriginal value. Therefore, Option A is the correct answer.

29. B, C, E. The constructors declared by Options A, D, and F compile without issue.Option B does not compile. Since there is no call to a parent constructor or constructorin the same class, the compiler inserts a no-argument super() call as the first line ofthe constructor. Because Big does not have a no-argument constructor, the no-argument constructor Trouble()does not compile. Option C also does not compilebecause super() and this() cannot be called in the same constructor. Note that if thesuper() statement was removed, it would still not compile since this would be arecursive constructor call. Finally, Option E does not compile. There is no matchingconstructor that can take a String followed by a long value. If the input argument deep

was an int in this constructor, then it would match the constructor used in Option Dand compile without issue.

30. E, F. A static method is not allowed to access instance variables without an instanceof the class, making Options E and F correct. Notice that only max is initialized to 100in Option E. Since min doesn’t have a value specified, it gets the default value, which is0.

31. B, E. The ternary ? : operator only evaluates one of the two right-hand expressions atruntime, so Option A is incorrect. A switch statement may contain at most oneoptional default statement, making Option B correct. A single if-then statement canhave at most one else statement, so Option C is incorrect. Note that you can join if-then-else statements together, but each else requires an additional if-then statement.The disjunctive | operator will always evaluate both operands, while the disjunctiveshort-circuit || operator will only evaluate the right-hand side of the expression if theleft-hand side evaluates to false. Therefore, they are not interchangeable, especially ifthe right-hand side of the expression modifies a variable. For this reason, Option D isincorrect. Finally, Option E is correct. The logical complement ! operator may only beapplied to boolean expressions, not numeric ones.

32. C. Line 3 creates an empty StringBuilder. Line 4 adds three characters to it. Line 5removes the first character resulting in ed. Line 6 deletes the characters starting atposition 1 and ending right before position 1. Since there are no indexes that meet thatdescription, the line has no effect. Therefore, Option C is correct.

33. A, D. Java methods must start with a letter, the dollar $ symbol, or the underscore _character. For this reason, Option B is incorrect, and Options A and D are correct.Despite how Option A looks, it is a valid method signature in Java. Options C, E, and Fdo not compile because the symbols -, \, and # are not allowed in method names,respectively.

34. B, C. First off, Option A is incorrect, since whether or not static or inherited methodsare chosen is a matter of design and individual preference. Options B and C are truestatements about inheritance and two of the most important reasons Java supportsinheritance. Option D is incorrect because all Java classes extend java.lang.Object.Option E is incorrect. Whether or not inheritance simplifies or complicates a design isbased on the skills of the developer creating the application.

35. E. All of the statements are true statements about Java, making Option E the correctanswer. Java was built with object-oriented programming and polymorphism in mind.Also, Java supports functional programming using lambda expressions.

36. C. This array has three elements, making listing.length output 3. It so happens thateach element references an array of the same size. But the code checks the firstelement and sees it is an array of size two, making the answer Option C.

37. A, B, E. A switch statement supports the primitive types byte, short, char, and int andtheir associated wrapper classes Character, Byte, Short, and Integer. It also supports

the String class and enumerated types. Floating-point types like float and double arenot supported, nor is the Object class. For these reasons, Options A, B, and E arecorrect.

38. D. The lambda syntax is incorrect. It should be ->, not =>. Therefore, Option D iscorrect. If this was fixed, Option A would be correct.

39. B, C, E. The /* */ syntax can have additional (and uneven) * characters in Java,making Options B and E correct. Option C is the standard way to comment a singleline with two slashes //. Option A contains a */ in the middle of the expectedcomment, making the part after the comment Insert **/ invalid. Option D isincorrect because a single slash / is not valid comment in Java. Finally, the # is not acomment character in Java, so Option F is incorrect.

40. A, F. A static import is used to import static members of another class. Option A iscorrect because the method getGrass and variable seeds are imported. Option F is alsocorrect because a wildcard on the Grass class for all visible static members is allowed.Option B is incorrect because the wildcard must be on a class, not a package. OptionsC and E are incorrect since the keywords import and static are reversed. Option D isincorrect because the static keyword is missing.

41. D. When converting an array to a List, Java uses a fixed-sized backed list. This meansthat the list uses an array in the implementation. While changing elements to newvalues is allowed, adding and removing elements is not.

42. A, D. Variable names can begin with an underscore, making Option A correct. To usean underscore in a numeric literal, it must be between two digits, making Option Dcorrect.

43. B. While no arguments are passed from the command line, this doesn’t matterbecause the main() method redefines the args array. Remember that String valuessort alphabetically rather than by number. Therefore, 01 sorts before 1, and Option Bis correct.

44. D. The public modifier allows access members in the same class, package, subclass, oreven classes in other packages, while the static modifier allows access without aninstance of the class. For these reasons, Option D is the correct answer. Option A isincorrect because final is not related to access, and package-private prevents accessfrom classes outside the package. Option B is incorrect because class is not amodifier; it is a keyword. Option C is incorrect because instance is not a Java keywordor modifier, and protected prevents classes that are not subclasses and are outside thepackage from accessing the variable. Finally, Option E is incorrect. The defaultkeyword is for interface methods and switch statements, not class variables.

45. A. Looping through the same list multiple times is allowed. Notice how there are notbraces around the loops. This means that only the print statement is inside the loop.It executes four times. However, the println() only executes once at the end, makingOption A the answer.

46. C, D. The javac command compiles a .java file into a .class bytecode file, makingOption C a correct answer, while also making Options B, E, and F incorrect. The javaccommand compiles to a set of java instructions, or bytecode, not machine instructions,making Option A incorrect and Option D correct.

47. C. The parseInt() method returns an int primitive. Thanks to autoboxing, we can alsoassign it to an Integer wrapper class object reference. The char and short types aresmaller than int so they cannot store the result. Therefore, lines 3 and 4 compile, andOption C is correct.

48. B, D, F. The compiler will broaden the data type on a numeric value until it finds acompatible signature. There are two versions of the drive() methods that return avalue of 3, one that takes a short and one that takes a double. Option A is incorrectbecause boolean cannot be converted to either of these types and trying to do sotriggers a compiler error. Option B is correct because the data type short matches ourmessage signature. Options C and E are incorrect. Remember that int and long arelarger than short and will trigger different overloaded versions of drive() to be called,one that returns 5 and one that returns 2, respectively. Option D is correct. The bytevalue can be implicitly converted to short, and there are no other matching methodsignatures that take a byte value. Finally, Option F is correct because float can beimplicitly converted to double, and there is no other version of drive() that takes afloat value.

49. A. Trick question. This appears to be about equality, but it is really about yourecognizing that the main() method is missing the static keyword. Running thisproblem gives a runtime exception because the main() method is not properlydeclared. Therefore, Option A is the answer. If this was fixed, the answer would beOption C because the int and String comparisons return true.

50. D. The code compiles without issue, so Options E and F are incorrect. Note that line p2accesses a static method using an instance reference, which is discouraged butpermitted in Java. First, a varargs int array of [0,0] is passed to the swing() method.The try block throws ArrayIndexOutOfBoundsException, since the third element isrequested and the size of the array is two. For this reason, the print() statement inthe try block is not executed. Next, since ArrayIndexOutOfBoundsException is asubclass of RuntimeException, the RuntimeException catch block is executed and 2 isprinted. The rest of the catch blocks are skipped, since the first one was selected. Thefinally block then executes and prints 4. Lastly, control is returned to the main()method without an exception being thrown, and 5 is printed. Since 245 is printed,Option D is the correct answer.

51. E. In the first iteration through the loop, container is 2 and cup is printed. Notice howthe loop body subtracts 1 to account for indexes being zero based in Java. Then theupdate statement runs, setting container to 3. The condition is run and sees that 3 isin fact greater than 0. The loop body subtracts 1 and tries to get the element at index 2.There isn’t one and the code throws an exception. This makes Option E correct. You

might be tempted to think this is an infinite loop. If the body did not throw anexception, it would be!

52. A, E, F. An entry point in a Java application consists of a main() method with a singleString[] or vararg String... argument, return type of void, and modifiers public andstatic. Note that the name of the variable in the input argument does not matter andthe final modifier is optional. Options A, E, and F match this description and arecorrect. Option B is incorrect because the argument is a single String. Option C isincorrect, since the access modifier is incorrectly marked protected. Finally, Option Dis incorrect because it has two return types, int and void.

53. C, D, E. For this question, it helps to remember that the value of a case statementmust be a literal expression or a final constant variable, and have a compatible datatype. For these reasons, Lines 10 and 12 do not compile, making Options C and Ecorrect answers. Line 10 uses a constant value, but long is not compatible with switchstatements, while Line 12 uses a variable that is not marked final. Next, a switchstatement may only have one default block. Therefore, Line 11 or 14 must beremoved. Since Line 14 is not in the list of options, Option D becomes the last correctanswer. The rest of the lines are fine since removing Lines 10, 11, and 12 allows thecode to compile.

54. A, B, C. All of the compilation issues with this code involve access modifiers. First, allinterface methods are implicitly public, and explicitly setting an interface method toprotected causes a compilation error on line h1, making Option A correct. Next, linesh2 and h3 both override the interface method with the package-private access modifier.Since this reduces the implied visibility of public, the overrides are invalid and neitherline compiles. Therefore, Options B and C are also correct. Note that theRuntimeException is allowed in an overridden method even though it is not in theparent method signature because only new checked exceptions in overridden methodscause compilation errors. Line h4 is valid. An object can be implicitly cast to asuperclass or inherited interface. Finally, lines h5 and h6 will compile without issuebut independently throw a ClassCastException and a NullPointerException atruntime, respectively. Since the question only asks about compilation problems,neither of these are correct answers.

55. B, E, F. Unchecked exceptions inherit the RuntimeException class and are not requiredto be caught in the methods where they are declared. Since ArithmeticException andIllegalArgumentException extend RuntimeException, they are included as uncheckedexceptions, making Options B, E, and F correct. The rest are checked exceptions, whichinherit Exception but not RuntimeException.

56. F. The code compiles without issue, making Options D and E incorrect. Applying theternary ? : operator, the variable ship is assigned a value of 10.0. The expression inthe first if-then statement evaluates to true, so Goodbye is printed. Note that there isno else statement between the first and second if-then statements, therefore thesecond if-then statement is also executed. The expression in the second if-then

statement evaluates to false, so the else statement is called and See you again is alsoprinted. Therefore, Option F is the correct answer, with two statements being printed.

57. B, C, D. The clock variable is accessed by a class in the same package; therefore, itrequires package-private or less restrictive access (protected and public). ThegetTime() method is accessed by a subclass in a different package; therefore, itrequires protected or less restrictive access (public). Options B, C, and D conform tothese rules, making them the correct answer. Options A and F cause the Snooze classto fail to compile because the getTime() method is not accessible outside the package,even though Snooze is a subclass of Alarm. Option E causes the Coffee class to fail tocompile because the clock variable is only visible within the Alarm class.

58. B. This problem appears to be to be about overriding a method, but in fact, it is muchsimpler. The class CarbonStructure is not declared abstract, yet it includes anabstract method. To fix it, the definition of CarbonStructure would have to bechanged to be an abstract class, or the abstract modifier would need to be removedfrom getCount() in CarbonStructure and a method body added. Since the only answerchoice available is to change the getCount() method on line q1, Option B is the correctanswer. Note that the rest of the application, including the override on line q2, iscorrect and compiles without issue. The return types Long and Number are covariantsince Number is a superclass of Long. Likewise, the exception thrown in the subclassmethod is narrower, so no compilation error occurs on q2.

59. C. Line 5 does not declare a main() method that can be the entry point to the program.It does correctly declare a regular instance method and does compile. Line 6 does notcompile because LocalDate needs to use a static method rather than a constructor.Line 7 is incorrect because Period methods should not be chained. However, it doescompile, returning a period of 1 day. Line 8 does not compile because the correct classname is DateTimeFormatter. Line 9 is correct. Option C is correct because lines 6 and 8do not compile.

60. A, E. A try block can have zero or more catch blocks, and zero or one finally blocks,but must be accompanied by at least one of these blocks. For these reasons, Options B,D, and F are incorrect, and Option E is correct. A finally block must appear after thelast catch block, if there are any, making Option C incorrect, and Option A correct.

61. B. The code compiles without issue, so Option E is incorrect. For this problem, it helpsto remember that + and * have a higher precedence than the ternary ? : operator. Inthe first expression, 1 + 2 * 5 is evaluated first, resulting in a reduction to 11>=2 ? 4: 2, and then fish being assigned a value of 4. In the second expression, the firstternary expression evaluates to false resulting in a reduction to the second right-handexpression 5>=5 ? 9 : 7, which then assigns a value of 9 to mammals. In the print()statement, the first + operator is an addition operator, since the operands arenumbers, resulting in the value of 4 + 9, 13. The second + operator is a concatenationsince one of the two operands is a String. The result 13 is printed, making Option Bthe correct answer.

62. A, C, E. An object can be cast to a superclass or inherited interface type without anexplicit cast. Furthermore, casting an object to a reference variable does not modifythe object in any way; it just may change what methods and variables are immediatelyaccessible. For these reasons, Options A, C, and E are correct. Option B is incorrect;since the compiler can try to block or warn about invalid casts, it cannot prevent them.For example, any object can be implicitly cast to java.lang.Object, then explicitly castto any other object, leading to a ClassCastException at runtime. Option D is alsoincorrect because assigning an object to a subclass reference variable requires anexplicit cast. Finally, Option F is incorrect. An object can always be cast to one of itsinherited types, superclass or interface, without a ClassCastException being thrown.

63. F. The array is not sorted. It does not meet the pre-condition for a binary search.Therefore, the output is not guaranteed and the answer is Option F.

64. B. While shoe3 goes out of scope after the shopping() method, the croc object isreferenced by shoe1 and therefore cannot be garbage collected. Similarly, the sandalobject is now referenced by shoe2. No variables reference the flip flop object, so it iseligible to be garbage collected, and Option B is correct.

65. E. The throws keyword is used in method declarations, while the throw keyword isused to throw an exception to the surrounding process, and the finally keyword isused to add a statement that is guaranteed to execute even if an exception is thrown.For these reasons, Option E is the correct answer.

66. B, E. The first two iterations through the loop complete successfully, making Option Bcorrect. However, the two arrays are not the same size and the for loop only checksthe size of the first one. The third iteration throws anArrayIndexOutOfBoundsException, making Option E correct.

67. E. For this question, it helps to try all answers out. Most of them do not make anysense. For example, overloading a method is not a facet of inheritance. Likewise,concrete and abstract methods can both be overridden, not just one. The only answerthat is valid is Option E. Without virtual methods, overriding a method would not bepossible, and Java would not truly support polymorphism.

68. E. The code does compile. Line s1 is a bit tricky because length is used for an arrayand length() is used for a String. Line s1 stores the length of the Fall in a variable,which is 4. Line s2 throws an ArrayIndexOutOfBoundsException because 4 is not avalid index for an array with four elements. Remember that indices start countingwith zero. Therefore, Option E is correct.

69. D. The code definitely does not compile, so Option A is incorrect. The first problemwith this code is that the Drum class is missing a constructor causing the classdeclaration on line 8 to fail to compile. The default no-argument constructor cannotbe inserted if the superclass, Instrument, does not define a no-argument constructor.The second problem with the code is that line 11 does not compile, since it callssuper.play(5), but the version of play() in the parent class does not take any

arguments. Finally, line 15 does not compile. While mn may be a reference variable thatpoints to a Drum() object, the concert() method cannot be called unless it is explicitlycast back to a Drum reference. For these three reasons, the code does not compile, andOption D is the correct answer.

70. B. The application compiles and runs without issue, so Options E and F are incorrect.Java uses pass-by-value, so even though the change to length in the first line of theadjustPropellers() method does not change the value in the main() method, thevalue is later returned by the method and used to reassign the length value. The resultis that length is assigned a value of 6, due to it being returned by the method. For thesecond parameter, while the String[] reference cannot be modified to impact thereference in the calling method, the data in it can be. Therefore, the value of the firstelement is set to LONG, resulting in an output of 6,LONG, making Option B the correctanswer.

71. D. The first compilation problem with the code is that the second catch block inopenDrawbridge() is unreachable since CableSnapException is a subclass ofOpenDoorException. The catch blocks should be ordered with the more narrowexception classes before the broader ones. Next, the variable ex is declared twicewithin the same scope since it appears in the second catch block as well as theembedded try-catch block. Finally, the openDrawbridge() method declares the checkedException class, but it is not handled in the main() method with a try-catch block, norin the main() method declaration. For these three reasons, Option D is correct.

72. D. Object orientation is the property of structuring an object with its related data andmethods. Encapsulation is the property of removing direct access to the underlyingdata from processes outside the class. The two go hand and hand to improve classdesign, making Option D the correct choice.

73. E. In Java, String is a class and not a primitive. This means it needs to begin with anuppercase letter in the declaration. The code does not compile, making Option Ecorrect. If this was fixed, the answer would be Option B.

74. A. This class is called with three command-line arguments. First the array is sorted,which meets the pre-condition for binary search. At this point, the array contains[flower, plant, seed]. The key is to notice the value of args[0] is now flower ratherthan seed. Calling binary search to find the position of flower returns 0, which is theindex matching that value. Therefore, the answer is Option A.

75. B, C, D. A for-each loop is a specialized loop that just iterates through an array or list.It can be rewritten using explicit indexing code in any of the other three loop types.Therefore, Options B, C, and D are correct. Option A is incorrect because a do-whileloop is guaranteed to execute at least once. Option E is incorrect because thetraditional for loop can loop backwards or by skipping indexes. Option F is incorrectbecause non-index-related boolean conditions are allowed to be used in a while loop.

76. E. The LocalDate class is only for day/month/year values. It does not support time, so

getHour() and plusHours() do not compile, making Option E the answer.

77. C. All arrays are objects regardless of whether they point to primitives or classes. Thatmeans both balls and scores are objects. Both are set to null so they are eligible forgarbage collection. The balls array is initialized to all null references. There are noobjects inside. The scores array is initialized to all 0 values. Therefore, only twoobjects exist to be eligible for garbage collection, and Option C is correct.

78. B. Since there are not brackets around the while loop, only line 17 is in the loop body.Line 18 gets executed once after the loop completes. This means that count will be 1assuming the loop completes. Subtracting a month from JANUARY results in DECEMBER.Since the loop completes E is incorrect and Option B is the answer. Note that if thebrackets were added as the indentation suggests, Option D would be the answer sincewe are counting months backwards.

79. D. Line 10 does not compile because the override reduces the visibility of an inheritedmethod, with the package-private modifier being more restrictive than the protectedmodifier. Line 11 does also not compile, since the left-hand side of a compoundassignment operator must be used with a variable, not a method. Finally, Line 12 doesnot compile because super.grunt() is inherited as an abstract method in thePolarBear class, meaning the parent class has no implementation. For these threereasons, Option D is the correct answer.

80. B, E. Package-private, or default, access is denoted by the absence of an accessmodifier, making Option A incorrect. Option B is correct, since a switch statement cancontain a default execution path. Options C and F are incorrect because keywords inJava cannot be used as method or variable names. Finally, interfaces can containdefault interface methods but they must be concrete with a method body. For thisreason, Option E is correct and Option D is incorrect.

Chapter 11: Java Class Design1. D. The toString() method is declared in the Object class. Therefore it is available to

be called in any Java class and is overridden in some. Java automatically calls thetoString() method when you print an object, making Option D correct. Option C isincorrect because toString() is a method, not a variable.

2. B. This code is not a singleton because it has a public constructor. Remember that apublic no-argument constructor is provided automatically if no constructor is coded.This code is well encapsulated because the instance variable is private. It is notimmutable since there is a setter method. Therefore, Option B is correct.

3. C. The singleton pattern ensures there will be no more than one instance of the object.Depending on how it is implemented, it is possible for there to be zero instances. Butit is not possible to have more than one, making Option C correct. Option D means thevariable is shared across instances or even without an instance being created but doesnot limit the number of the instances of the class itself.

4. C. Both objects are instances of the class Laptop. This means the startup() method inthe Laptop class gets called both times thanks to polymorphism.

5. D. We know that the variable o that equals() is called on isn’t null, since we can’t callinstance methods on a null reference. However, a null reference could be passed as amethod parameter. If a null is passed in, the method should return false since anobject and a null are not equal. Options A and B are incorrect because the first line ofthose methods should return false rather than true. Option C is incorrect because thecast is missing. The Object class does not have a text variable available. Option Dshows a properly implemented equals() method and is correct.

6. A. Option A is correct because mutability means the state can change andimmutability means it cannot. In Option C, static means the state isn’t tied to aninstance. In Option B, rigidity is not a common programming term.

7. B. The Hammer class is a subclass of the Tool class. Since the use() method in Hammer isintended to override the one in Tool, there are certain rules. One is that the accessmodifier must not be more specific. Therefore, trying to make it private is a problem.Option B is correct and r2 is the only line with a compiler error in this code.

8. D. The singleton pattern requires that only one instance of the class exist. Neither ofthese classes meets that requirement since they have the default no-argumentconstructor available. There should have been a private constructor in each class.Therefore, Option D is correct. Remember that the exam doesn’t always includeimport statements to simplify the code you need to read.

9. B. While using null with instanceof compiles, it always returns false. The other twoinstanceof calls show that instanceof can be used with both classes and interfaces.They both return true, making Option B correct.

10. D. The static keyword is used to create a class-level variable, making Option Dcorrect. Note that a singleton is where you limit a class so only one instance can becreated. This means there are not multiple instances to share a variable across.

11. A. Option A is a requirement of a singleton class rather than an immutable one. Theother three options are requirements of an immutable class.

12. C. If the variables are public, the class is not encapsulated because callers have directaccess to them. This rules out Options A and B. Having private methods doesn’t allowthe callers to use the data, making Option D an undesirable answer. Option C iscorrect and the classic definition of encapsulation where the data is not exposeddirectly.

13. A. While both objects are instances of Laptop, we are not calling methods in thisexample. Virtual method invocation only works for methods, not instance variables.For instance variables, Java actually looks at the type of the reference and calls theappropriate variable. This makes each reference call a different class’s instancevariable in this example, and Option A is correct.

14. B. An immutable class must not allow the state to change. In the Flower class, thecaller has a reference to the List being passed in and can change the size or elementsin it. Similarly, any class with a reference to the object can get the List by callingget() and make these changes. The Flower class is not immutable. The Plant classshows how to fix these problems and is immutable. Option B is correct.

15. C. An instance method can access both instance variables and static variables. Bothmethods compile and Option C is correct.

16. B. A static method can access static variables, but not instance variables. ThegetNumRakes() method does not compile, so Option B is correct.

17. A. You are allowed to use null with instanceof; it just prints false. The bus variable isboth a Vehicle and a Bus, so lines 18 and 19 print true. Then it gets interesting. Weknow that bus is not an ArrayList or Collection. However, the compiler only knowsthat bus is not an ArrayList because ArrayList is a concrete class. Line 20 does notcompile. The compiler can’t definitively state that bus is not a Collection. Some futureprogram could create a subclass of Bus that does implement Collection, so this linecompiles. Therefore, only line 20 fails to compile, and Option A is correct.

18. B. Building and House are both properly declared inner classes. Any House object canbe stored in a Building reference, making the declarations for p and r compile. Thedeclaration for s is also correct. It so happens that bh is a House object, so the castworks. The declaration of q is a problem though. While the cast itself is fine, aBuilding cannot be stored in a House reference, which means the assignment fails tocompile. Option B is correct and is the only line with a compiler error in this code.Note that if the declaration of q was removed, the declaration of p would produce aClassCastException at runtime.

19. D. If two instances of a class have the same hash code, they might or might not beequal. The reverse is not true. If two objects are equal, they must have the same hashcode in order to comply with the contracts of these methods. However, in this case,the answer is none of the above because the method can’t simply return true or false.Based on the rules of equals(), if null is passed in, the result must be false. If anobject identity is passed in, the result must be true due to reflexivity. As a result,Option D is correct.

20. D. This class is a good example of encapsulation. It has a private instance variable andis accessed by a public method. No changes are needed to encapsulate it, and OptionD is correct.

21. B. The singleton pattern requires that only one instance of the class exist. TheExamAnswers class is close. However, getExamAnswers() is not static, so you can’tretrieve the instance. Option B is the answer because TestAnswers is a correctimplementation. It has a static variable representing the one instance and a staticmethod to retrieve it.

22. C. The static initializer is only run once. The static method is run twice since it iscalled twice. Therefore, three lines are printed, and Option C is correct.

23. C. Option A is allowed because the turnOn() method is public and can be called fromanywhere. Options B and D are allowed since the method is in the same class, which isalways allowed! Option C is not allowed because wash() is a package-private method inanother package. Option C is the correct answer.

24. B. The display() method has protected access. This means it can be accessed byinstance methods in the same package and any subclasses. There are no subclasses inthis example, so we only need to count the classes in the same package. Option B iscorrect because Flashlight and Phone are in the package.

25. B. Line 15 calls the method on line 9 since it is a Watch object. That returns watch,making Option A incorrect. Line 16 calls the method on line 3 since it is a SmartWatchobject and the method is properly overridden. That returns smart watch, so Option Bis the answer, and Option C is incorrect.

26. A. Clearly a Bus is a Vehicle since the Bus class implements Vehicle. The Van class isalso a Vehicle since it extends Bus. This question also confirms you know that arrayscan be tested with instanceof, which they can. Therefore, Option A is correct.

27. C. There is no instanceOf keyword, making Options B and D incorrect. There is aninstanceof keyword. If an object is the wrong type, the equals() method shouldreturn false, making Option C the answer.

28. D. The Hammer class is a subclass of the Tool class. Luckily, the use() method has adifferent signature so it is not an override. This means it is fine that the accessmodifier is stricter, and Option D is correct. Line r3 is a valid method unrelated to thesuperclass.

29. B. Lazy instantiation is part of a possible implementation for the singleton pattern. Itdefers creating the object until the first caller requests it. While this does savememory, it only does so if the object is never requested. This does not save memorywhen actually creating the object. Option B is correct.

30. D. Notice how the code begins at line 30. This means you have to infer thesurrounding code. Here it is reasonable to assume the classes are inner classes.Building and House are defined correctly. Any House or Building reference canpotentially be a House. The compiler does not know which ones work and which don’t.This means all three casts compile.

31. C. Encapsulation doesn’t allow callers access to the instance variables, which makes iteasier to change the code. The instance variables can be any type, which means theycan be mutable or immutable. There are not constraints on the implementation ofmethods. The purpose of encapsulation is to lessen how tightly tied or coupled theclasses are. Option C is the opposite of this, making it the answer.

32. A. An immutable class must not allow the state to change. The Flower class does thiscorrectly. While the class isn’t final, the getters are, so subclasses can’t change thevalue returned. The Plant class lacks this protection, which makes it mutable. OptionA is correct.

33. D. A static initializer is not allowed inside of a method. It should go on the class levelrather than the method level. Therefore, the code does not compile, and Option D iscorrect.

34. A. An object is required to have the same value for repeated calls to hashCode() if thevalue has not changed. This makes III and IV incorrect. If two objects are equal, theyare required to have the same hash code. Since equality must be reflexive, it cannotreturn false if the same object is passed, and I is incorrect. Since equals() mustreturn false when null is passed in, it cannot be true and II is incorrect. Therefore,Option A is the answer.

35. D. By definition, you cannot change the value of an instance variable in an immutableclass. There are no setter methods, making Option A incorrect. While Option B wouldallow you to set the value, the class would no longer be immutable. Option D iscorrect. If you are an advanced developer, you might know that you can use reflectionto change the value. Don’t read into questions like this on the exam. Reflection isn’ton the exam, so you can pretend it doesn’t exist.

36. B. Option A is incorrect because the “is-a” principle is about inheritance. For example,a String is an Object. Option C is incorrect because singletons require a staticvariable to ensure there is only one instance. While it is common to have instancevariables as well, this is not required to implement the pattern. Option B is correct.For an object to be composed of other objects, instance variables are required.

37. B. The static initializer only runs once since statics are shared by all instances. Theinstance initializer runs twice because we call the constructor twice. Therefore, Option

B is correct.

38. A. While there is a default keyword in Java, it is only allowed in interfaces or inswitch statements. It is not a visibility modifier. The author of this code probablyintended for the method to be package-private, which doesn’t use a visibility modifier.The line with default doesn’t compile, so Option A is correct. If default was removed,the code would all compile.

39. A. The reference b points to a Building object, which cannot be stored in a Housereference. This means the assignment to p compiles but fails at runtime. The othertwo casts would run without issue if the code got that far.

40. C. The hashCode() method in the Object class does not have a parameter. Therefore,the Sticker class provides an overloaded method rather than an overridden one. Sinceit is not an overridden method, the contract for the Object class’ hashCode() methoddoes not apply, and any int value can be returned. Therefore, Option C is correct.

Chapter 12: Advanced Java Class Design1. B. The lambda expression s -> true is valid, making Options A, C, and D incorrect.

Parentheses () are not required on the left-hand side if there is only one variable.Brackets {} are not required if the right-hand side is a single expression. Parameterdata types are only required if the data type for at least one parameter is specified,otherwise none are required. The remaining choice, the arrow operator ->, is requiredfor all lambda expressions, making Option B the correct answer.

2. D. The application contains a compilation error. The case statements incorrectly usethe enum name as well as the value, such as DaysOff.ValentinesDay. Since the type ofthe enum is determined by the value of the variable in the switch statement, the enumname is not allowed and throws a compilation error when used. For this reason,Option D is correct. If the enum name DaysOff was removed, the application wouldoutput 12, since the lack of any break statements causes multiple blocks to be reached,and Option C would have been the correct answer.

3. C. A functional interface must include exactly one abstract method, either byinheritance or declared directly. It may also have any number, including zero, ofdefault or static methods. For this reason, both parts of Option D are incorrect. Thefirst part of Option A is incorrect because more than one abstract method disqualifiesit as a functional interface. The first part of Option B is incorrect because the methodmust be abstract; that is to say, any method will not suffice. Finally, Option C is thecorrect answer. The first part of the sentence defines what it means to be a functionalinterface. The second part refers to the optional @FunctionalInterface annotation. Itis considered a good practice to add this annotation to any functional interfaces youdefine because the compiler will report a problem if you define an invalid interfacethat does not have exactly one abstract method.

4. C. While an anonymous inner class can extend another class or implement aninterface, it cannot be declared final or abstract since it has no class definition. Forthis reason, Option C is correct. The other classes may be declared final or abstractsince they have a class definition.

5. B. Option A is incorrect because the lambda expression is missing a semicolon (;) atthe end of the return statement. Option C is incorrect because the local variable testis used without being initialized. Option D is also incorrect. The parentheses arerequired on the left-hand side of the lambda expression when there is more than onevalue or a data type is specified. Option B is the correct answer and the only validlambda expression.

6. B. An enum cannot be marked abstract, nor can any of its values, but its methods canbe marked abstract, making Option B the correct answer. Note that if an enumcontains an abstract method, then every enum value must include an override of thisabstract method.

7. B. The code compiles without issue, so Option D is incorrect. The first print()

statement refers to value in the Deeper class, so 5 is printed. The second and thirdprint() statements actually refer to the same value in the Deep class, so 2 is printedtwice. The prefix Matrix. is unnecessary in the first of the two print() statements anddoes not change the result. For these reasons, Option B is the correct answer.

8. D. A local inner class can access final or effectively final local variables, makingOption D the correct answer. The second statement is invalid because access modifierslike private cannot be applied to local variables.

9. C. The type of the variable in the switch statement is the enum Currency, but the casestatements use int values. While the enum class hierarchy does support an ordinal()method, which returns an int value, the enum values cannot be compared directlywith int values. For this reason, the code does not compile, since the case statementvalues are not compatible with the variable type in the switch statement, makingOption C the correct answer.

10. C. A local variable is effectively final when it’s primitive value or object reference doesnot change after it is initialized, making Option C the correct answer. Option D isincorrect. Any change to the variable after it is initialized disqualifies it for beingconsidered effectively final.

11. D. Both the Drive and Hover interfaces define a default method getSpeed() with thesame signature. In fact, both getSpeed() methods return the same value of 5. Theclass Car implements both interfaces, which means it inherits both default methods.Since the compiler does not know which one to choose, the code does not compile, andthe answer is Option D. Note that if the Car class had overridden the getSpeed()method, then the code would have compiled without issue and printed 10 at runtime.In particular, the local class Racecar defined in the main() method compiles withoutissue, making Option C incorrect.

12. B. An interface can be extended by another interface and a class can be extended byanother class, making the second part of Options A, C, and D incorrect. Option B iscorrect because an enum cannot be extended. Note that Option C is also incorrect forthis reason.

13. B. If the program is called with a single input WEST, then WEST would be printed atruntime. If the program is called with no input, then the compass array would be ofsize zero, and an ArrayIndexOutOfBoundsException would be thrown at runtime.Finally, if the program is called with a string that does not match one of the values inDirection, then an IllegalArgumentException would be thrown at runtime. The onlyresult not possible is south, since the enum value is in uppercase, making Option Bthe correct answer.

14. B. Enumerated types support creating a set of reusable values whose values are fixedand consistent across the entire application. For these reason, Options A, C, and D areincorrect. Option B is the false statement because enum values are defined at compiletime and cannot be changed or added at runtime.

15. D. The program contains three compilation problems. First off, the enum Colorextends the enum Light, but enums cannot extend other enums so the definition isinvalid. Second, the enum value list must end with a semicolon (;) if the enumdefinition contains anything other than the enum values. Since it includes aconstructor, a semicolon (;) is required after GREEN. Finally, enum constructors mustbe private, meaning the protected constructor for Color does not compile. For thesethree reasons, Option D is the correct answer.

16. D. Both abstract classes and interfaces can include static methods, so Options A andC are incorrect. A static nested class can include static methods, but it is the only typeof inner class in which this is allowed. Local inner classes, anonymous inner classes,and member inner classes do not support static methods. For these reasons, OptionD is correct, and Option B is incorrect.

17. B. A functional interface must contain exactly one abstract method. The Bendinterface contains two abstract methods, pump() and bend(), since it extends Pump andinherits pump(). For this reason, the Bend method is not a valid functional interfaceand therefore cannot be used as a lambda expression, making Option B the correctanswer. The rest of the code compiles without issue. Note that the usage of aninstance variable to call a static method, r.apply() in the main() method, ispermitted but discouraged.

18. C. Applying the @Override annotation is optional and not required to override amethod or implement an interface method, making Options A and B incorrect. Whilepartially helpful as a form of documentation, it is not the best reason to apply theannotation, making Option D incorrect. The best reason is that the compiler willactually fail to compile if the method that the @Override annotation is being applied tois not actually overriding an inherited method. This behavior helps correct typos orchanges in superclasses or interfaces that could break the class or lead to unexpectedbehavior. For this reason, Option C is the best choice.

19. C. The Bottle class includes a static nested class Ship that must be instantiated in astatic manner. Line w2 uses an instance of Bottle to instantiate the Ship. While thiswould be allowed if Ship was a member inner class, since it is a static nested class, linew2 does not compile, and Option C is the correct answer. Note that if Ship was changedto be a member inner class, the code would still not compile since a member innerclass cannot include static members and enums are inherently static. Therefore, thecorrect change would be to fix the declaration on line w2.

20. A. Option A is the invalid lambda expression because the type is specified for thevariable j, but not the variable k. The rest of the options are valid lambda expressions.To be a valid lambda expression, the type must be specified for all of the variables, asin Option C, or none of them, as in Options B and D.

21. D. This application declares an anonymous inner class that implements the Edibleinterface. Interface methods are public, whereas the override in the anonymous innerclass uses package-private access. Since this reduces the visibility of the method, the

declaration of eat() on line 8 does not compile. Next, the declaration of the appleobject must end with a semicolon (;) on line 11, and it does not. For these tworeasons, the code does not compile, and Option D is the correct answer. Note that ifthese two issues were corrected, with the public modifier and missing semi-colon (;),then the correct answer would be Option A because the code does not actually call theeat() method; it just declares it.

22. A. The code compiles without issue and prints 15, making Option A correct and OptionD incorrect. The main() method defines a local class Oak that correctly extends Tree, astatic nested class, making Option B incorrect. Finally, the method getWater() ispermitted to read the variable water, defined in the main() method, since it iseffectively final, having a value of 15 when it is defined. For this reason, Option C isalso incorrect.

23. C. Interfaces allow Java to support multiple inheritance because a class mayimplement any number of interfaces. On the other hand, an anonymous inner classmay implement at most one interface, since it does not have a class definition toimplement any others. For these reasons, Option C is the correct answer.

24. A. The code does not compile because the declaration of isDanger() in the classSeriousDanger is an invalid method override. An overridden method may not throw abroader checked exception than it inherits. Since Exception is a superclass of Problem,thrown by the inherited method in the Danger class, the override of this checkedexception is invalid. For this reason, line m1 does not compile, and Option A is thecorrect answer. The rest of the lines of code compile without issue.

25. B. Options A, C, and D are true statements about interfaces and abstract classes.Option B is the correct answer because neither abstract classes nor interfaces can bemarked final. For Option D, methods and variables can both be marked private inabstract classes in some cases. The “some cases” refers to the fact that the privatemodifier cannot be applied to abstract methods, since a method cannot be markedboth final and abstract. Since abstract classes can contain concrete methods, whichcan take the private access modifier, the statement is true.

26. A. The code compiles without issue, so Option C is incorrect. Enum ordinal values areindexed starting with zero, so 0 is printed first. The second line compiles and runswithout issue, with flurry being converted to FLURRY, using the toUpperCase()method. Since there is a matching enum named FLURRY, that value is printed next. Forthese reasons, Option A is the correct answer.

27. D. Java was updated to include default interface methods in order to supportbackward compatibility of interfaces. By adding a default method to an existinginterface, we can create a new version of the interface, which can be used withoutbreaking the functionality of existing classes that implement an older version of theinterface. For this reason, Option D is the correct answer. Options A and C are notapplicable to default interface methods, whereas Option B could be achieved by usingstatic interface methods.

28. C. The Penguin class includes a member inner class Chick. Member inner classescannot include static methods or variables. Since the variable volume is markedstatic, the member inner class Chick does not compile, making Option C the correctanswer. Note that the variable volume referenced in the chick() method is one definedin the Penguin outer class. If the static modifier was removed from the volumevariable in the Chick class, then the rest of the code would compile and run withoutissue, printing Honk(1)! at runtime.

29. D. Member inner classes require an instance of the surrounding class to beinstantiated. Option A is incorrect since we are told that the instantiation request isfrom a static method. Note that this call would be valid from a non-static method inDinosaur. Option B is incorrect because it lacks the new keyword. Option C is incorrect.Pterodactyl is a member inner class, not a static nested class. Option D is correct anduses the instance dino to create a new Pterodactyl object.

30. C. First off, both CanBurrow and HasHardShell are functional interfaces since theycontain exactly one abstract method, although only the latter uses the optional@FunctionalInterface annotation. The declarations of these two interfaces, alongwith the abstract class Tortoise, compile without issue, making Options A and Bincorrect. The code does not compile, though, so Option D is incorrect. The classDesertTortoise inherits two abstract methods, one from the interface CanBurrow andthe other from the abstract parent class Tortoise. Since the class only implements oneof them and the class is concrete, the class declaration of DesertTortoise fails tocompile on line k3, making Option C the correct answer.

31. B. First off, the two interface definitions contain identical methods, with the publicmodifiers assumed in all interfaces methods. For the first statement, the write()method is marked default in both interfaces, which means a class can only implementboth interfaces if the class overrides the default method with its own implementationof the method. Since the Twins method does override write(), the method compileswithout issue, making the first statement incorrect. Next, the publish() method ismarked static in both interfaces and the Twins class. While having a static methodin all three is allowed, marking a static method with the @Override annotation is notbecause only member methods may be overridden. For this reason, the secondstatement is correct. Finally, the think() method is assumed to be abstract in bothinterfaces since it doesn’t have a static or default modifier and does not define abody. The think() method is then correctly overridden with a concreteimplementation in the Twins class, making the third statement incorrect. Since onlythe second statement was true, Option B is the correct answer.

32. D. An enum and static inner class can define static methods, making Option D thecorrect answer. Options A, B, and C are incorrect because the other types of innerclasses cannot define static methods. Note that interfaces and abstract classes candefine static methods.

33. C. First off, Option A does not compile since the variables p and q are reversed, making

the return type of the method and usage of operators invalid. The first argument p is aString and q is an int, but the lambda expression reverses them, and the code doesnot compile. Option B also does not compile. The variable d is declared twice, first inthe lambda argument list and then in the body of the lambda expression. The seconddeclaration in the body of the lambda expression causes the compiler to generate aduplicate local variable message. Note that other than it being used twice, theexpression is valid; the ternary operator is functionally equivalent to the learn()method in the BiologyMaterial class. Option C is the correct answer since it compilesand handles the input in the same way as the learn() method in the BiologyMaterialclass.

34. C. The code does not compile since it contains two compilation errors, making OptionA incorrect. First, the enum list is not terminated with a semicolon (;). A semicolon(;) is required anytime an enum includes anything beyond just the list of values, suchas a constructor or method. Second, the access modifier of TRUE’s implementation ofgetNickName() is package-private, but the abstract method signature has a protectedmodifier. Since package-private is a more restrictive access than protected, theoverride is invalid and the code does not compile. For these two reasons, Option C isthe correct answer. Note that the @Override annotation is optional in the methodsignature, therefore FALSE’s version of getNickName() compiles without issue. Also,note that the Proposition constructor does not include a private access modifier, butthe constructor compiles without issue. Enum constructors are assumed to be privateif no access modifier is specified, unlike regular classes where package-private isassumed if no access modifier is specified.

35. A. The code compiles and runs without issue, printing 8 at runtime, making Option Acorrect and Option D incorrect. The AddNumbers interface is a valid functionalinterface. While it includes both static and default methods, it only includes oneabstract method, the precise requirement for it to be considered a functionalinterface, making Option B incorrect. Finally, Option C is incorrect because thelambda expression is valid and used correctly.

36. A. While this code included a large number of final modifiers, none of them preventthe code from compiling when a valid expression is placed in the blank, makingOption D incorrect. Option B is incorrect since it returns the size variable defined inthe Insert member inner class, not the Bottle class, printing 25 at runtime. Option Cis incorrect because the expression is invalid and does not compile when inserted intothe blank. Finally, Option A is the correct answer because it compiles, properlyreferences the variable size in the Bottle class, and prints 14 at runtime.

37. C. The main() method attempts to define an anonymous inner class instance but failsto provide the class or interface name, or use the new keyword. The right-hand side ofthe assignment to the seaTurtle variable should start with new CanSwim(). For thisreason, Option C is the correct answer. If the code was corrected with the properdeclaration, it would output 7, and Option B would be the correct answer.

38. D. The code does not compile, so Options A and B are incorrect. The declarations ofthe local inner classes Robot and Transformer compile without issue. The anonymousinner class that extends Transformer compiles without issue, since the public variablename is inherited, making Option C incorrect. The only compilation problem in thisclass is the last line of the main() method. The variable name is defined inside the localinner class and not accessible outside class declaration without a reference to the localinner class. Due to scope, this last line of the main() method does not compile, makingOption D the correct answer. Note that the first part of the print() statement in themain() method, if the code compiled, would print GiantRobot.

39. B. The Dancer class compiles without issue, making Option A incorrect. TheSwingDancer class, though, does not compile because getPartner() is an invalidmethod override. In particular, Leader and Follower are not covariant since Followeris not a subclass of Leader. Therefore, line u2 does not compile, making Option Bcorrect and Option D incorrect. Note that the abstract method getPartner(int) is notimplemented in SwingDancer, but this is valid because SwingDancer is an abstractclass and is not required to implement all of the inherited abstract methods.

40. C. The code does not compile, so Options A and B are incorrect. The problem here isthat the DEFAULT_VALUE is an instance variable, not a static variable; therefore, thestatic nested class GetSet cannot access it without a reference to the class. For thisreason, the declaration of the static nested class GetSet does not compile, and OptionC is the correct answer. The rest of the code compiles without issue. Note that if theDEFAULT_VALUE variable was modified to be static, then the code would compilewithout issue, and Option B would be the correct answer.

Chapter 13: Generics and Collections1. C. When declaring a class that uses generics, you must specify a name for the formal

type parameter. Java uses the standard rules for naming a variable or class. A questionmark is not allowed in a variable name, making I incorrect. While it is commonpractice to use a single uppercase letter for the type parameter, this is not required. Itcertainly isn’t a good idea to use existing class names like the News class being declaredhere or the Object class built into java. However, this is allowed, and Option C iscorrect.

2. B. Option A is incorrect because the filter() method is available on Stream, but notList. Option C is incorrect because the replace() method is available on List, but notStream. Option D is tricky because there is a sort() method on List and a sorted()method on Stream. These are different method names though, so Option D isincorrect. Option B is the answer because both interfaces have a forEach() method.

3. A. Notice how there is unnecessary information in this description. The fact thatpatrons select books by name is irrelevant. The checkout line is a perfect example of adouble-ended queue. We need easy access to one end of the queue for patrons to addthemselves to the queue. We also need easy access to the other end of the queue forpatrons to get off the queue when it is their turn. The book lookup by ISBN is a lookupby key. We need a map for this. A HashMap is probably better here, but it isn’t a choice.So the answer is Option A, which does include both a double-ended queue and a map.

4. B. Java talks about the collections framework, but the Map interface does not actuallyimplement the Collection interface. TreeMap has different methods than ArrayDequeand TreeSet. It cannot fill in the blank, so Option B is correct.

5. B. Options C and D are incorrect because the method signature is incorrect. Unlike theequals() method, the method in Comparator takes the type being compared as theparameters when using generics. Option A is a valid Comparator. However, it sorts inascending order by length. Option B is correct. If s1 is three characters and s2 is onecharacter, it returns -2. The negative value says that s1 should sort first, which iscorrect, because we want the longest String first.

6. D. TreeMap and TreeSet keep track of sort order when you insert elements. TreeMapsorts the keys and TreeSet sorts the objects in the set. This makes Option D correct.Note that you have the option of having JellyBean implement Comparable, or you canpass a Comparator to the constructor of TreeMap or TreeSet.

7. C. Option A is incorrect because a pipeline still runs if the source doesn’t generate anyitems and the rest of the pipeline is correct. Granted some of the operations havenothing to do, but control still passes to the terminal operation. Option B is incorrectbecause intermediate operations are optional. Option C is the answer. The terminaloperation triggers the pipeline to run.

8. B. The Iterator interface uses the hasNext() and next() methods to iterate. Since

there is not a hasMore() method, it should be changed to hasNext(), making Option Bthe answer. With respect to Option A, the missing generic type gives a warning, butthe code still runs. For Option C, iterators can run as many times as you want, as canthe forEach() method on list.

9. A. First the code creates an ArrayList of three elements. Then the list is transformedinto a TreeSet. Since sets are not allowed to have duplicates, the set only has twoelements. Remember that a TreeSet is sorted, which means that the first element inthe TreeSet is 3. Therefore, Option A is correct.

10. C. The word reduction is used with streams for a terminal operation, so Options A andB are incorrect. Option D describes a valid terminal operation like anyMatch(), but isnot a reduction. Option C is correct because a reduction has to look at each element inthe stream in order to determine the result.

11. A. The offer() method adds an element to the back of the queue. After line 7completes, the queue contains 18 and 5 in that order. The push() method adds anelement to the front of the queue. How rude! The element 13 pushes past everyone onthe line. After line 8 completes, the queue now contains 13, 18, and 5, in that order.Then we get the first two elements from the front, which are 13 and 18, making OptionA correct.

12. D. The Magazine class doesn’t implement Comparable<Magazine>. It happens toimplement the compareTo() method properly, but it is missing actually writingimplements Comparable. Since TreeSet doesn’t look to see if the object can becompared until runtime, this code throws a ClassCastException when TreeSet callsadd(), so Option D is correct.

13. C. Line 8 does not compile. String::new is a constructor reference. A constructor ormethod reference is equivalent to a lambda. It participates in deferred execution.When it is executed later, it returns a String. It does not return a String on line 8. Itactually returns a Supplier<String>, which cannot be stored in list. Since the codedoes not compile, Option C is correct.

14. B. This code adds two elements to a list. It then gets a stream and iterates through thelist, printing two lines. The last line does the same thing again. Since a fresh stream iscreated, we are allowed to iterate through it, and Option B is correct.

15. D. The Comic interface declares a formal type parameter. This means that a classimplementing it needs to specify this type. The code on line 21 compiles because thelambda reference supplies the necessary context making Option A incorrect. Option Bdeclares a generic class. While this doesn’t tell us the type is Snoopy, it punts theproblem to the caller of the class. The declaration of c2 on line 22 compiles because itsupplies the type, making Option B incorrect. The code on line 23 compiles becausethe SnoopyClass itself supplies the type making Option C incorrect. Option D has aproblem. SnoopyClass and SnoopyComic appear similar. However, SnoopyComic refers toC. This type parameter exists in the interface. It isn’t available in the class because the

class has said it is using Snoopy as the type. Since the SnoopyComic class itself doesn’tcompile, the line with c4 can’t instantiate it, and Option D is the answer.

16. A. In streams, the filter() method filters out any values that do not match. Thismeans the only value to make it to the terminal operator count() is Chicago, andOption A is correct.

17. C. When implementing Comparable, you implement the compareTo() method. Sincethis is an instance method, it already has a reference to itself and only needs the itemit is comparing. Only one parameter is specified, and Option C is correct. By contrast,the Comparator interface uses the compare() method and the method takes twoparameters.

18. C. The source and any intermediate operations are chained and eventually passed tothe terminal operation. The terminal operation is where a non-stream result isgenerated, making Option C correct.

19. A. A constructor reference uses the new keyword where a method name wouldnormally go in a method reference. It can implicitly take zero or one parameters justlike a method reference. In this case, we have one parameter, which gets passed to theconstructor. Option A is correct.

20. D. A custom sort order is specified using a Comparator to sort in descending order.However, this Comparator is not passed when searching. When a different sort order isused for searching and sorting, the result is undefined. Therefore, Option D is correct.

21. D. Java only allows you to operate on a stream once. The final line of code throws anIllegalStateException because the stream has already been used up. Option D is thecorrect answer.

22. D. The Wash class takes a formal type parameter named T. Option C shows the best wayto call it. This option declares a generic reference type that specifies the type is String.It also uses the diamond syntax to avoid redundantly specifying the type on the right-hand side of the assignment. Options A and B show that you can omit the generic typein the reference and still have the code compile. You do get a compiler warningscolding you for having a raw type. But compiler warnings do not prevent compilation.With the raw type, the compiler treats T as if it is of type Object. That is OK in thisexample because the only method we call is toString() implicitly when printing thevalue. Since toString() is defined on the Object class, we are safe, and Options A andB work. Since all three can fill in the blank, Option D is the answer.

23. D. The missing generic type gives a warning, but the code still runs, so Option A isincorrect. The Iterator interface uses hasNext() and next() methods to iterate, soOption B is incorrect. Option C applies to calling the same stream twice. One of ourcalls is to an Iterator anyway, so Option C is incorrect. This code is in fact correct,making the answer Option D.

24. B. This is a static method reference. It uses :: to separate the class name and method

name. Option B is correct.

25. B. A source and the terminal operation are required parts of a stream pipeline andmust occur exactly once. The intermediate operation is optional. It can appear zero ormore times. Since more than once falls within zero or more, Option B is correct.

26. B. ArrayList allows null elements, making Option B correct. TreeSet does not allownulls because they need to compare the values. ArrayDeque uses null for a specialmeaning, so it doesn’t allow it in the data structure either.

27. D. Option A is the only one of the three options to compile. However, it results in nolines being output since none of the three strings are empty. Options B and C do noteven compile because a method reference cannot have an operator next to it.Therefore, Option D is correct.

28. A. Unfortunately you do have to memorize two facts about sort order. First, numberssort before letters. Second, uppercase sorts before lowercase. Since TreeMap orders bykey, the first key is 3 and the last is three, making Option A correct.

29. C. The ? is an unbounded wildcard. It is used in variable references but is not allowedin declarations. In a static method, the type parameter specified inside the <> is usedin the rest of the variable declaration. Since it needs an actual name, Options A and Bare incorrect. We need to specify a type constraint so we can call the add() method.Regardless of whether the type is a class or interface, Java uses the extends keywordfor generics. Therefore, Option D is incorrect, and Option C is the answer.

30. B. On a stream, the filter() method only keeps values matching the lambda. TheremoveIf() does the reverse on a Collection and keeps the elements that do notmatch. In this case, that is Austin and Boston so Option B is correct.

31. D. The code correctly creates an ArrayDeque with three elements. The stream pipelinedoes compile. However, there is no terminal operation, which means the stream isnever evaluated and the output is something likejava.util.stream.ReferencePipeline$2@404b9385. This is definitely not one of thelisted choices, so Option D is correct.

32. C. The forEach() method that takes one parameter is defined on the Collectioninterface. However, a map is not a Collection. There is a version of forEach() definedon the Map interface, but it uses two parameters. Since two parameters can’t be usedwith a method reference, Option C is the answer.

33. C. This code is almost correct. Calling two different streams is allowed. The codeattempts to use a method reference when calling the forEach() method. However, itdoes not use the right syntax for a method reference. A double colon needs to be used.The code would need to be changed to System.out::println to work and print twolines for each call. Since it does not compile, Option C is correct.

34. B. This code shows a proper implementation of Comparable. It has the correct methodsignature. It compares the magazine names in alphabetical order. Remember that

uppercase letters sort before lowercase letters. Since Newsweek is uppercase, Option Bis correct.

35. C. The filter() method requires a boolean returned from the lambda or methodreference. The getColor() method returns a String and is not compatible. This causesthe code to not compile and Option C to be correct.

36. A. Option A is correct as the source and terminal operation are mandatory parts of astream pipeline. Option B is incorrect because a Stream must return non-primitives.Specialized interfaces like IntStream are needed to return primitives. Option C isincorrect because Stream has methods such as of() and iterate() that return aStream. Option D is incorrect because infinite streams are possible.

37. B. The stream pipeline is correct and filters all values out that are 10 characters orsmaller. Only San Francisco is long enough, so c is 1. The stream() call creates a newobject, so stream operations do not affect the original list. Since the original list is still3 elements, Option B is correct.

38. B. Options A and C are incorrect because a generic type cannot be assigned to anotherdirect type unless you are using upper or lower bounds in that statement. Now, we justhave to decide whether a lower or upper bound is correct for the T formal typeparameter in Wash. The clue is that the method calls size(). This method is availableon Collection and all classes that extend/implement it. Therefore, Option B is correct.

39. C. A Comparator takes two parameters, so Options A and B are incorrect. Option Ddoesn’t compile. When using brackets, a return keyword and semicolon are required.Option C is a correct implementation.

40. B. Option D is incorrect because there is a charAt() instance method. While Option Cis correct that the method takes in an int parameter, autoboxing would take care ofconversion for us if there were no other problems. So Option C is not the answer.Option A is not true because there are constructor and instance method references.Option B is the answer. With method references, only one item can be supplied atruntime. Here, we need either a String instance with no parameters in the method ora static method with a single parameter. The charAt() method is an instance methodwith a single parameter so does not meet this requirement.

Chapter 14: Lambda Built-in Functional Interfaces1. C. The Supplier functional interface does not take any inputs, while the Consumer

functional interface does not return any data. This behavior extends to the primitiveversions of the functional interfaces, making Option C the correct answer. Option A isincorrect because IntConsumer takes a value, while LongSupplier returns a value.Options B and D are incorrect because Function and UnaryOperator both take an inputand produce a value.

2. A. The LongSupplier interface does not take any input, making Option D incorrect. Italso uses the method name getAsLong(). The rest of the functional interfaces all takea long value but vary on the name of the abstract method they use. LongFunctioncontains apply() and LongPredicate contains test(), making Options B and C,respectively, incorrect. That leaves us with LongConsumer, which contains accept(),making Option A the correct answer.

3. A. The code compiles without issue, so Options C and D are incorrect. The value fordistance is 2, which based on the lambda for the Predicate will result in a trueexpression, and Saved will be printed, making Option A correct.

4. C. Both are functional interfaces in the java.util.function package, making Option Atrue. The major difference between the two is that Supplier<Double> takes the generictype Double, while the other does not take any generic type and instead uses theprimitive double. For this reason, Options B and D are true statements. ForSupplier<Double> in Option B, remember that the returned double value can beimplicitly cast to Double. Option C is the correct answer. Lambdas forSupplier<Double> can return a null value since Double is an object type, whilelambdas for DoubleSupplier cannot; they can only return primitive double values.

5. B. The lambda (s,p) -> s+p takes two arguments and returns a value. For this reason,Option A is incorrect because BiConsumer does not return any values. Option D is alsoincorrect, since Function only takes one argument and returns a value. This leaves uswith Options B and C, which both use BiFunction, which takes two generic argumentsand returns a generic value. Option C is incorrect because the datatype of the unboxedsum s+q is int and int cannot be autoboxed or implicitly cast to Double. Option B iscorrect. The sum s+p is of type double, and double can be autoboxed to Double.

6. C. To begin with, ToDoubleBiFunction<T,U> takes two generic inputs and returns adouble value. Option A is compatible because it takes an Integer and Double andreturns a Double value that can be implicitly unboxed to double. Option B iscompatible because long can be implicitly cast to double. While we don’t know thedata types for the input arguments, we know that some values, such as using Integerfor both, will work. Option C cannot be assigned and is the correct answer because thevariable v is of type Object and Object does not have a length() method. Finally,Option D is compatible. The variable y could be declared double in the genericargument to the functional interface, making y/z a double return value.

7. C. The BiPredicate interface takes two generic arguments and returns a booleanvalue. Next, DoubleUnaryOperator takes a double argument and returns a double value.Last, ToLongFunction takes a generic argument and returns a long value. That leavesOption C, which is the correct answer. While there is an ObjDoubleConsumer functionalinterface, which takes a generic argument and a double value and does not return anydata, there is no such thing as ObjectDoubleConsumer. Remember that Object isabbreviated to Obj in all functional interfaces in java.util.function.

8. C. The code does not compile, so Options A and D are incorrect. The IntUnaryOperatorfunctional interface is not generic, so the argument IntUnaryOperator<Integer> in thetakeTicket() does not compile, making Option C the correct answer. The lambdaexpression compiles without issue, making Option B incorrect. If the genericargument <Integer> was dropped from the argument declaration, the class wouldcompile without issue and output 51 at runtime, making Option A the correct answer.

9. A. Option A is the correct answer because BiPredicate takes two generic types andreturns a primitive boolean value. Option B is incorrect, since CharSupplier does notexist in java.util.function. Option C is also incorrect, since LongFunction takes aprimitive long value and returns a generic type. Remember, Java only includesprimitive functional interfaces that operate on double, int, or long. Finally, Option Dis incorrect. UnaryOperator takes a generic type and returns a generic value.

10. D. First off, the forEach() method requires a Consumer instance. Option C can beimmediately discarded because Supplier<Double> does not inherit Consumer. For thissame reason, Option B is also incorrect. DoubleConsumer does not inherit fromConsumer. In this manner, primitive functional interfaces cannot be used in theforEach() method. Option A seems correct, since forEach() does take a Consumerinstance, but it is missing a generic argument. Without the generic argument, thelambda expression does not compile because the expression p<5 cannot be applied toan Object. The correct functional interface is Consumer<Double>, and since that is notavailable, Option D is the correct answer.

11. C. BiFunction<Double,Double,Double> and BinaryOperator<Double> both take twoDouble input arguments and return a Double value, making them equivalent to oneanother. On the other hand, DoubleFunction<Double> takes a single double value andreturns a Double value. For this reason, it is different from the other two, makingOption C correct and Option D incorrect.

12. B. BinaryOperator<Long> takes two Long arguments and returns a Long value. For thisreason, Option A, which takes one argument, and Option D, which takes two Integervalues that do not inherit from Long, are both incorrect. Option C is incorrect becausethe local variable c is re-declared inside the lambda expression, causing the expressionto fail to compile. The correct answer is Option B because intValue() can be called ona Long object. The result can then be cast to long, which is autoboxed to Long.

13. C. The program does not compile, so Option A is incorrect. The Supplier functionalinterface normally takes a generic argument, although generic types are not strictly

required since they are removed by the compiler. Therefore, line d1 compiles whiletriggering a compiler warning, and Options B and D are incorrect. On the other hand,line d2 does cause a compiler error, because the lambda expression does not return avalue. Therefore, it is not compatible with Supplier, making Option C the correctanswer.

14. A. The input type of a unary function must be compatible with the return type. Bycompatible, we mean identical or able to be implicitly cast. For this reason, Option A isthe correct answer. Option B is incorrect since all of the UnaryOperator functionalinterfaces, generic or primitive, take exactly one value. Option C is incorrect becausethe primitive functional interfaces do not take a generic argument. Finally, Option D isincorrect. For example, the generic UnaryOperator<T> returns an Object that matchesthe generic type.

15. C. Remember that all Supplier interfaces take zero parameters. For this reason, thethird value in the table is 0, making Options A and B incorrect. Next, DoubleConsumerand IntFunction each take one value, double and int, respectively. On the other hand,ObjDoubleConsumer takes two values, a generic value and a double, and returns void.For this reason, Option C is correct, and Option D is incorrect.

16. D. All Consumer functional interfaces have a void return type. For this reason, the firstand last values in the table are both void, making Options A and B incorrect.IntFunction takes an int and returns a generic value, while LongSupplier does nottake any values and returns a long value. For this reason, Option C is incorrect, andOption D is correct.

17. B. The removeIf() method requires a Predicate since it operates on a boolean result,making Option A incorrect. The forEach() method takes a Consumer and does notreturn any data, making Option B correct, and Options C and D incorrect.

18. C. The code does not compile, so Option A is incorrect. The lambda expressioncompiles without issue, making Option B incorrect. The task variable is of typeUnaryOperator<Doll>, with the abstract method apply(). There is no accept() methoddefined on that interface, therefore the code does not compile, and Option C is thecorrect answer. If the code was corrected to use the apply() method, the rest of itwould compile without issue. At runtime, it would then produce an infinite loop. Oneach iteration of the loop, a new Doll instance would be created with 5, since the post-decrement (--) operator returns the original value of the variable, and that wouldmake Option D the correct answer.

19. C. To begin with, Consumer uses accept(), making Option A incorrect. Next, Functionand UnaryOperator use apply(), making Options B and D, respectively, incorrect.Finally, Supplier uses get(), making Option C the correct answer.

20. D. First off, Options A and B are incorrect because the second functions for bothreturn a double or Double value, respectively. Neither of these values can be sent to aUnaryOperator<Integer> without an explicit cast. Next, Option C is incorrect. The first

functional interface Function<Double,Integer> takes only one input, but the diagramshows two inputs for the first functional interface. That leaves us with Option D. Thefirst functional interface BiFunction<Integer,Double,Integer> takes an int, whichcan be implicitly autoboxed to Integer, and a Double and returns an Integer. The nextfunctional interface, BinaryOperator<Integer>, takes two Integer values and returnsan Integer value. Finally, this Integer value can be implicitly unboxed and sent toIntUnaryOperator, returning an int. Since these behaviors match our diagram, OptionD is the correct answer.

21. D. Options A, B, and C are true statements about functional interfaces. A lambda maybe compatible with multiple functional interfaces, but it must be assigned to afunctional interface when it is declared or passed as a method argument. Also, amethod can be created with the return type that matches a functional interface,allowing a lambda expression to be returned. Option D is the correct answer. Deferredexecution means the lambda expression is not evaluated until runtime, but it iscompiled. Compiler errors in the lambda expression will prevent the code fromcompiling.

22. B. Option A is incorrect because the String "3" is not compatible with the return typeint required for IntSupplier. Option B is the correct answer. Although this will resultin a divide by zero issue at runtime, the lambda is valid and compatible withIntSupplier. Option C is incorrect because the lambda expression is invalid. Thereturn statement is only allowed inside a set of brackets {}. Finally, Option D isincorrect. The method reference is used for Supplier, not Consumer, since it takes avalue and does not return anything.

23. C. The lambda expression is invalid because the input argument is of type Boss, andBoss does not define an equalsIgnoreCase() method, making Option C the correctanswer. If the lambda was corrected to use s.getName() instead of s, the code wouldcompile and run without issue, printing [JENNY, GRACE] at runtime and makingOption A the correct answer.

24. D. First of all, Consumer<Object> takes a single Object argument and does not returnany data. The classes ArrayList and String do not contain constructors that take anObject, so neither of the first two statements are correct. The third statement doessupport an Object variable, since the System.out.println(Object) method exists. Forthese reasons, Option D is the correct answer.

25. B. The java.util.function package does not include any functional interfaces thatoperate on the primitive float, making Option A incorrect. Remember, Java onlyincludes primitive functional interfaces that operate on double, int, or long. Option Bis correct because it is a valid functional interface. Option C is incorrect because thereis no UnaryIntOperator functional interface. Note that there is one calledIntUnaryOperator. Option D is incorrect. The java.util.function package does notinclude any tri- operators, although many are easy to write.

26. D. A lambda expression can match multiple functional interfaces. It matches

DoubleUnaryOperator, which takes a double value and returns a double value. Notethat the data type of s+1 is double because one of the operands, in this case s, isdouble. It also matches Function<String,String> since the (+) operator can be usedfor String concatenation. Finally, it matches IntToLongFunction since the int values+1can be implicitly cast to long. On the other hand, the lambda expression is notcompatible with UnaryOperator without a generic type. When UnaryOperator is usedwithout a generic argument, the type is assumed to be Object. Since the (+) operator isnot defined on Object, the code does not compile due to the lambda expression body,making Option D the correct answer. Note that if the lambda expression did not relyon the (+) operator, such as s -> s, then UnaryOperator would be allowed by thecompiler, even without a generic type.

27. B. The BiFunction interface takes two different generic values and returns a genericvalue, taking a total of three generic arguments. Next, ToDoubleFunction takes exactlyone generic value and returns a double value, requiring one generic argument. TheToIntBiFunction interface takes two generic values and returns an int value, for atotal of two generic arguments. For these reasons, Options A, C, and D are incorrect.The correct answer is Option B. DoubleFunction takes a double value and returns ageneric result, taking exactly one generic argument, not two.

28. D. While lambda expressions can use primitive types as arguments, the functionalinterface in this class uses the wrapper classes, which are not compatible. For thisreason, Option A is incorrect. Option B is also incorrect, since the number ofarguments and return type does not match the functional interface. Furthermore, themethod reference System.out::print on the right-hand side of the lambda expressionis invalid here, since it returns a method reference, not a double value. Option C isincorrect because 2*w is of type double, which cannot be returned as an Integerwithout an explicit cast. Option D is the correct answer. It takes exactly two argumentsbecause the return value int can be implicitly autoboxed to Integer.

29. A. BooleanSupplier is the only functional interface that does not involve double, int,or long, making Option A the correct answer. The rest of the functional interfaces arenot found in java.util.function. Java does not have built-in support for primitivefunctional interfaces that include char, float, or short.

30. D. The code does not compile because the lambda expression p -> p*100 is notcompatible with the DoubleToIntFunction functional interface. The input to thefunctional interface is double, meaning p*100 is also double. The functional interfacerequires a return value of int, and since double cannot be implicitly cast to int, thecode does not compile, making Option D the correct answer. If the correct cast wasapplied to make (p*100) an int, then the rest of the class would compile and 250would be printed at runtime, making Option B correct.

31. B. The ToDoubleFunction interface takes a generic value, not a double value, makingOption D incorrect. It also uses the method name accept(). The rest of the functionalinterfaces all take a double value. DoubleConsumer contains the accept() method,

making Option A incorrect. DoublePredicate contains the test() method, makingOption B the correct answer. Finally, DoubleUnaryOperator contains theapplyAsDouble() method, making Option C incorrect.

32. D. To start with, line 5 does not compile because Function takes two genericarguments, not one. Second, the assignment statement on line 7 does not end with asemicolon (;), so it also does not compile. Finally, the forEach() method on line 10requires a Consumer, not a Function, so this line does not compile. For these threereasons, Option D is the correct answer.

33. D. The DoubleToLongFunction interface takes a double argument and returns a longvalue. Option A is compatible since the int value 1 can be implicitly cast to long, and2L is already a long. Option B is also compatible, since the double value 10.0*e isexplicitly cast to int then implicitly cast to long. Next, Option C is compatible becausean explicit cast of the double to a long value is used. Option D cannot be assigned andis the correct answer. Although the Double class does have a longValue() method, theleft-hand side of the lambda expression must use the primitive double, not thewrapper Double. This lambda expression violates the signature of the functionalinterface, since it allows Double values to be sent to the interface, including those thatcould be null.

34. C. The DoublePredicate interface takes a double value and returns a boolean value.LongUnaryOperator takes a long value and returns a long value. ToIntBiFunction takestwo generic values and returns an int value. The only choice that is not an existingfunctional interface is ShortSupplier. Recall that Java only includes primitivefunctional interfaces that operate on double, int, or long. For this reason, Option C isthe correct answer.

35. A. The method reference System.out::println takes a single input and does notreturn any data. Consumer<Sheep> is compatible with this behavior, making Option Athe correct answer and Option D incorrect. Option B is incorrect because void cannotbe used as a generic argument. Option C is incorrect since System.out::println()does not return any data and UnaryOperator requires a return value.

36. C. The code does not compile, making Options A and B incorrect. The local variableMAX_LENGTH is neither final nor effectively final, meaning it cannot be used inside thelambda expression. The MAX_LENGTH variable starts off with an initial value of 2, butthen is modified with the increment assignment (+=) operator to a value of 5,disqualifying its ability to be considered effectively final by the compiler. Since thelambda does not compile, Option C is the correct answer. If the code was rewritten sothat the MAX_LENGTH variable was marked final and assigned a value of 5 from thestart, then it would output 2, and Option A would be correct.

37. B. To begin with, all of the functional interfaces in the list of choices take two values.The difference is in the name of the method they use. BiConsumer uses accept(),making Option A incorrect. Option B is correct because BiFunction includes theapply() method. Option C is incorrect, since BiPredicate uses the test() method.

DoubleBinaryOperator is almost correct but the name of the method isapplyAsDouble(), not apply(), making Option D incorrect. For the exam, you shouldbe aware of which primitive functional interfaces use a different method name thanthe generic ones.

38. B. To start with, IntFunction<Integer> takes an int value and returns an Integer. Thefirst statement uses Integer instead of int as the input argument and is therefore notcompatible. The second statement is compatible, since the return type null can beused as an Integer return type. The last statement is also valid. An int can beautoboxed to Integer. For these reasons, Option B is the correct answer.

39. C. The primitive Supplier functional interfaces, such as BooleanSupplier andLongSupplier, do not have a get() method. Instead, they have methods such asgetAsBoolean() and getAsLong(), respectively. For this reason, the first line of thecheckInventory() method does not compile, making Option C the correct answer. Ifthe method call was changed to getAsBoolean(), then the rest of the code wouldcompile without issue, print Plenty! at runtime, and Option A would be the correctanswer.

40. B. Java only supports a single return data type or void. Therefore, it is not possible todefine a functional interface that returns two data types, making Option A incorrect.Although Java does not include built-in support for primitive functional interfacesthat include float, char, or short, there is nothing to prevent a developer fromcreating them in their own project, making Option B the true statement and thecorrect answer. Option C is incorrect because a functional interface that takes novalues and returns void is possible. In fact, Runnable is one such example. Option D isalso incorrect, since IntFunction<R> takes a primitive argument as input and a genericargument for the return type.

Chapter 15: Java Stream API1. D. Option A is incorrect because it doesn’t print out one line. The peek() method is an

intermediate operation. Since there is no terminal operation, the stream pipeline isnot executed, so the peek() method is never executed. Options B and C are incorrectbecause they correctly output one line using a method reference and lambda,respectively, and don’t use any bad practices. Option D is the answer. It does outputone line. However, it is bad practice to have a peek() method that has side effects likemodifying a variable.

2. A. This code generates an infinite stream of integers: 1, 2, 3, 4, 5, 6, 7, etc. ThePredicate checks if the element is greater than 5. With anyMatch(), the streampipeline ends once element 6 is hit and the code prints true. For both the allMatch()and noneMatch() operators, they see that the first element in the stream does notmatch and the code prints false. Therefore, Option A is correct.

3. B. Only the average() method returns an OptionalDouble. This reflects that it doesn’tmake sense to calculate an average when you don’t have any numbers. By contrast,counting without any numbers gives the long number 0 and summing gives the doublenumber 0.0. Since only one method matches the return type, Option B is correct.

4. C. The map() method can fill in the blank. The lambda converts a String to an int andJava uses autoboxing to turn that into an Integer. The mapToInt() method can also fillin the blank and Java doesn’t even need to autobox. There isn’t a mapToObject() in thestream API. Note there is a similarly named mapToObj() method on IntStream. Sinceboth map() and mapToInt() work here, Option C is correct.

5. D. The average() method returns an OptionalDouble. This interface has agetAsDouble() method rather than a get() method, so the code does compile.However, the stream is empty, so the optional is also empty. When trying to get thevalue, the code throws a NoSuchElementException, making Option D correct.

6. D. Option A is incorrect because anyMatch() returns a boolean. Option B is incorrectbecause filter() is an intermediate operation, not a terminal operation, and thereforereturns a Stream. Both of these methods do take a Predicate as a parameter. WhilefindAny() does return an Optional, it doesn’t take any parameters. Therefore, OptionC is incorrect, and Option D is the answer.

7. B. This code builds a list with two elements. It then uses that list as a source for thestream, sorts the stream as it goes by, and grabs the first sorted element. This does notchange the original list. The first element in the sorted stream is 1.2, but the firstelement of list remains as 5.4. This makes Option B correct.

8. B. Primitive streams, like LongStream, declare an average() method, while summarystatistics classes, like LongSummaryStatistics, declare a getAverage() method, makingOptions C and D incorrect. The average() method returns an OptionalDouble object,which declares a getAsDouble() method rather than a get() method. Therefore,

Option A is incorrect, and Option B is correct.

9. B. Since the result of the collect() is not stored in a variable or used in any way, allthe code needs to do is compile. There is no Collectors.toArrayList() method. If youwant to specify an ArrayList, you can call Collectors.toCollection(ArrayList::new).The Collectors.toList() method does in fact exist and compile. While there is aCollectors.toMap() method, it requires two parameters to specify the key and valuefunctions, respectively. Since only one can compile, Option B is correct.

10. C. As tempting as it is, you can’t actually convert a Map into a Stream directly, whichmeans you can’t call the map() method on it either. However, you can build a Streamout of the keys or values or key/value pairs. Since this code doesn’t compile, Option Cis correct.

11. D. I is incorrect because isPresent() returns false for an empty Optional. II isincorrect because of() throws a NullPointerException if you try to pass a nullreference. III doesn’t throw an exception as the ofNullable() is designed to allow anull reference. However, it returns false because no value is present. Since none ofthe choices are correct, Option D is the answer.

12. A. This code does compile. Remember that imports are implied, including the staticimport for Collectors. The collector tries to use the number of characters in eachstream element as the key in a map. This works fine for the first two elements, speakand bark, because they are of length 5 and 4, respectively. When it gets to meow, it seesanother key of 4. The merge function says to use the first one, so it chooses bark forthe value. Similarly, growl is 5 characters, but the first value of speak is used. Thereare only two distinct lengths, so Option A is correct.

13. C. For the primitive stream that contains the int primitives, the interface names areincorrect. They should be IntStream and IntSummaryStatistics, making Option Ccorrect. If this was fixed, Option B would be the answer.

14. B. This code does compile. As an intermediate operation, you are allowed to callpeek() many times in a stream pipeline. You can even call it multiple times in a row.While it is common to write System.out::println directly as a parameter to peek(),nothing prevents you from creating a Consumer variable. Since the forEach() methodalso takes a Consumer, we can reuse it. The three peek() intermediate operations andone forEach() operation total four lines of output. The map() operation could beomitted since it simply passes the input through.

15. B. Character objects are allowed in a Stream, so line z1 compiles, making Option Cincorrect. Line z2 also compiles since findAny() returns an Optional and ifPresent()is declared on Optional. Therefore, Option D is also incorrect. Now let’s look at theStream. The source has three elements. The intermediate operation sorts the elementsand then we request one from findAny(). The findAny() method is not guaranteed toreturn a specific element. Since we are not using parallelization, it is highly likely thatthe code will print a. However, you need to know this is not guaranteed, making

Option B the answer.

16. A. The sorted() method takes an optional Comparator as the parameter, which takestwo String parameters and returns an int. Option A is correct because the lambdaimplements this interface. Option B is incorrect because the method reference doesn’ttake any parameters, nor does it return an int.

17. D. The Optional class has an isPresent() method that doesn’t take any parameters. Itreturns a boolean and is commonly used in if statements. There is also anifPresent() method that takes a Consumer parameter and runs it only if the Optionalis non-empty. The methods isNotNull() and forEach()are not declared in Optional.Therefore, Option D is correct.

18. C. The first intermediate operation, limit(1), turns the infinite stream into a streamwith one element: true. The partitioningBy() method returns a map with two keys,true and false, regardless of whether any elements actually match. If there are nomatches, the value is an empty list, making Option C correct.

19. B. The flatMap() method is used to turn a stream of streams into a one-dimensionalstream. This means it gets rid of the empty list and flattens the other two. Option A isincorrect because this is the output you’d get using the regular map() method. OptionB is correct because it flattens the elements. Notice how it doesn’t matter that all threeelements are different types of Collection implementations.

20. D. The sorted() method allows an optional Comparator to be passed as a reference.However, Comparator.reverseOrder() does not implement the Comparator interface. Ittakes zero parameters instead of the required two. Since it cannot be used as a methodreference, the code does not compile, and Option D is correct.

21. D. Option A is incorrect because the findAny() might not return 1. The result could beany of the three numbers. Option B is incorrect because there is no first() methodavailable as a terminal operation. Option C is tempting because there is a min()method. However, since we are working with a Stream, this method requires aComparator as a parameter. Therefore, Option D is the answer.

22. C. List doesn’t have a filter() method, so Option A is incorrect. Stream does havefilter() and map() methods. However, Stream doesn’t have an ifPresent() method.This makes IV incorrect, so Options B and D are incorrect. Both Collection andString have an isEmpty() method, so either can be used with the Optional, makingOption C the answer.

23. D. This code generates an infinite stream of the number 1. The Predicate checks if theelement is greater than 5. This will never be true. With allMatch(), the streampipeline ends after checking the first element. It doesn’t match, so the code printsfalse. Both anyMatch() and noneMatch() keep checking and don’t find any matches.However, they don’t know if a future stream element will be different, so the codeexecutes infinitely until the process is terminated. Therefore, Option D is correct.

24. D. Both Collectors.groupingBy() and Collectors.partitioningBy() are useful forturning a stream into a Map. The other two methods do not exist. However, when usinga condition, you should use partitioningBy() as it automatically groups using aBoolean key. Therefore, Option D is correct.

25. B. Option A is incorrect because we are working with primitives rather than objects.Option C compiles but outputs the stream references rather than the contents. OptionB is correct because it flattens the int primitives into one stream.

26. D. The summary statistics classes provide getters in order to access the data. ThegetAverage() method returns a double and not an OptionalDouble. Option D is theonly option to compile.

27. D. Option A doesn’t compile because the get() method on Optional doesn’t take anyparameters. Options B and C do compile, but both print Cupcake since the Optional isnot empty. Therefore, Option D is correct.

28. C. The first line generates an infinite stream. The stream pipeline has a filter that letsall these elements through. Since sorted() requires all the elements be available tosort, it never completes, making Option C correct.

29. A. The mapToDouble() method compiles. However, it converts 9 into 9.0 rather thanthe single digit 9. The mapToInt() method does not compile because a long cannot beconverted into an int without casting. The mapToLong() method is not available onLongStream so it does not compile. It is available on DoubleStream, IntStream, andStream implementations. Since none of the options outputs the single digit 9, Option Ais correct.

30. A. The filter() method either passes along a given element or doesn’t, makingOption D incorrect. The flatMap() method doesn’t pass along any elements for emptystreams. For non-empty streams, it flattens the elements, allowing it to return zero ormore elements. This makes Option B incorrect. Finally, the map() method applies aone-to-one function for each element. It has to return exactly one element, so OptionA is the correct answer.

31. D. First, we sort the stream. Option B is incorrect because findFirst() is guaranteedto return the first element. However, the findFirst() method returns an Optional.Therefore, the output of this code is Optional[a] rather than the letter a, makingOption D correct.

32. C. There is not a stream pipeline method called sort(). There is one called sorted().Since the code does not compile, Option C is correct. If this was fixed, Option A wouldbe correct since the Comparator sorts in ascending order.

33. B. This code compiles. It creates a stream of Ballot objects. Then it creates a map withthe contestant’s name as the key and the sum of the scores as the value. For Mario,this is 10 + 9, or 19, so Option B is correct.

34. D. Both anyMatch() and allMatch() take a Predicate as a parameter. This code does

not compile because the parameter is missing.

35. D. The flatMap() method works with streams rather than collections. The code doesnot compile because the x is not a stream, making Option D correct. If this was fixed,Option B would be the answer.

36. C. The groupingBy() collector always returns a Map (or a specific implementation classof Map), so III can’t be right. The other two are definitely possible. To get I, you cangroup using a Function that returns an Integer such as s.collect(Collectors.groupingBy(String::length)). To get II, you need to group using a Function thatreturns a Boolean and specify the type, such as s.collect(Collectors.groupingBy(String::isEmpty, Collectors.toSet())). Notice that autoboxing is usedfor both. Therefore, Option C is correct.

37. D. There is no built-in method to map a value to a boolean primitive. Therefore,Options B and C don’t even compile, so they are incorrect. Option A does compile as itmaps a Runner to a Boolean. However, it doesn’t actually filter() the stream toeliminate any values, so the output is not the same. It prints 3 instead of 1. None ofthese are correct, making Option D the answer.

38. A. Option A is the answer because there is a getCount() method that returns a longrather than a method named getCountAsLong(). Option B is incorrect because there isin fact a getMax() method. Option C is incorrect because toString() is declared onObject, which means it is inherited by all classes.

39. C. The main() method has warnings, but it does compile, making Option D incorrect.The warnings are both about not declaring the generic type for Optional. Option Adoes not compile because the orElse() method expects an Exception as the alternatevalue passed as a parameter. IllegalArgumentException::new is a Supplier instead.Options B and C both compile as both methods expect a Supplier as the parameter.However, orElseGet() simply returns the exception from the method rather thanthrowing it. Option C actually throws the exception the Supplier created and is thecorrect answer.

40. B. Option A happens to output the same result for both pairs. It outputs a blank line inwithFlatMap() because empty streams are removed and in withoutFlatMap() becausethe filter() method removes the empty list. Option B outputs different results. ThewithFlatMap() method outputs lastall queued up since it flattens the streams. Bycontrast, the withoutFlatMap() method outputs [last, all queued up] since it leavesthe structure intact. Since the output is different. Option B produces different resultsso it is the answer.

Chapter 16: Exceptions and Assertions1. D. If no exception is thrown, then the catch block will not be executed. The try block

is always visited first, followed by the finally block, which is guaranteed to executeregardless of whether an exception is thrown. For these reasons, Option D is thecorrect answer, with the statements in the correct order.

2. C. Unlike a try-with-resources statement, in which the catch and finally blocks areoptional, a try statement requires a catch or finally block to be used, or both. Forthis reason, Option C is the correct answer.

3. D. The code does not compile because the throw keyword is incorrectly used in thetoss() method declaration. The keyword throws should have been used instead. Forthis reason, Option D is the correct answer. Since LostBallException inheritsThrowable and the main() method handles Throwable, LostBallException is handledby the main() method, making Option B incorrect. Option C is also incorrect becauseArrayStoreException is an unchecked exception that extends RuntimeException and isnot required to be handled or declared. Finally, if throws was used instead of throw,the entire application would compile without issue and print Caught!, making OptionA the correct answer.

4. A. The only symbol permitted to separate exception types in a multi-catch statement isa single pipe character (|). For this reason, Option A is correct.

5. D. In Java, assert is a keyword, meaning it cannot be used as a variable, class, ormethod name. For this reason, line 5 does not compile. Line 6 also does not compilebecause the assert statement is not a method and does not support parenthesesaround both expressions. Because neither of these lines compile, Option D is thecorrect answer.

6. C. First off, Error is an unchecked exception. It is recommended that Error not becaught by most application processes, making Option A incorrect.IllegalStateException inherits RuntimeException, both of which are unchecked,making Options B and D, respectively, incorrect. Option C is correct becauseParseException must be handled or declared.

7. D. The Exception class contains multiple constructors, including one that takesThrowable, one that takes String, and a no-argument constructor. The firstWhaleSharkException constructor compiles, using the Exception constructor that takesa String. The second WhaleSharkException constructor also compiles. The twostatements, super() and new Exception(), actually call the same constructor in theException class, one after another. The last WhaleSharkException compiles with thecompiler inserting the default no-argument constructor super(), because it exists inthe Exception class. For these reasons, all of the constructors compile, and Option D isthe correct answer.

8. B. The UnsupportedOperationException class is an unchecked exception, which means

it inherits from RuntimeException. While Error also is an unchecked exception, thediagram indicates that the class does not inherit from Error. There is only one classbetween Throwable and RuntimeException in the diagram, and since we knowRuntimeException inherits Exception, the other missing class must be Exception. Forthese reasons, Option B is the correct answer.

9. C. The code does not compile because the variable b is used twice in the main()method, both in the method declaration and in the catch block, making Option C thecorrect answer. If a different variable name was used in one of the locations, theprogram would print one line, complete, making Option A the correct answer. Notethat while an exception is created inside the turnOn() method, it is not thrown.

10. D. First off, unless assertions are enabled at runtime, no assertion statementguarantees an assertion will be thrown at runtime, making Option D the correctanswer. Next, Option A does not compile because the assert statement is not amethod and does not take arguments in parentheses. It’s also invalid because itrequires a boolean expression for the first expression, not a numeric one. Anadditional value can be specified, but it requires a colon separator (:). Option B wouldbe the correct answer and trigger an error if assertions are enabled, since 0==1evaluates to false. Option C is incorrect. Even if assertions were enabled, it would nottrigger an error since 0==0 evaluates to true.

11. C. The class does not compile because in line r2, brackets {} are used instead ofparentheses () in the try-with-resources statement, making Option C the correctanswer. If this line was fixed to use parentheses (), then the rest of the class wouldcompile without issue and print This just in! at runtime, making Option A thecorrect answer.

12. C. When both a try block and close() method throw exceptions, the one in the tryblock is the primary, while the one in the close() method is suppressed. For thisreason, Option A is a true statement. Option B is also a true statement, since a catchblock is not required when using a try-with-resources statement. Option C is thecorrect answer, since resources are closed in reverse order in which they are created,not the other way around. Option D is a true statement because multiple resourcescan be declared within a single set of parentheses, each separated by a semicolon (;).

13. A. The program compiles without issue, so Option D is incorrect. The narrowerSpellingException and NullPointerException, which inherit from Exception, arecorrectly presented in the first catch block, with the broader Exception being in thesecond catch block. The if-then statement evaluates to true, and a newSpellingException instance is created, but it is not thrown because it is missing thethrow keyword. For this reason, the try block ends without any of the catch blocksbeing executed. The finally block is then called, making it the only section of code inthe program that prints a line of text. For this reason, Option A is the correct answer.

14. C. First off, the try block is capable of throwing two checked exceptions,MissingMoneyException and MissingFoodException. The catch block uses the

Exception class to handle this, since both have Exception as a supertype. It thenrethrows the Exception. For this reason, Exception would be appropriate in the blank,making the first statement correct. The compiler is also smart enough to know thatthere are only two possible subclasses of Exception that can actually be thrown in themain() method, so declaring MissingMoneyException and MissingFoodExceptiontogether also allows the code to compile, making the third statement correct. Thesecond statement, only inserting MissingMoneyException, would not allow the code tocompile because the main() method could throw a checked MissingFoodException thatwas not handled. For these reasons, Option C is the correct answer.

15. C. First off, Closeable extends AutoCloseable, making Option A incorrect. Thedifference between the two is that the close() method in AutoCloseable throwsException, while the close() method in Closeable throws IOException, makingOption D incorrect. Since IOException is a subclass of Exception, both close()methods can throw an IOException, making Option B incorrect. On the other hand,Exception is not a subclass of IOException. For this reason, the close() method in aclass that implements Closeable cannot throw an instance of the Exception class,because it is an invalid override using a broader exception type, making Option C thecorrect answer.

16. B. Option A does not compile because a multi-catch expression uses a single variable,not two variables. Option C does not compile because it is not possible to throw thischecked IOException in the try block. Option D does not compile because multi-catchblocks cannot contain two exceptions in which one is a subclass of the other. If it did,one of the two exceptions would be redundant. Option B is the correct answer and theonly expression that allows the class to compile. While both exceptions in the multi-catch block inherit from Exception, neither is a subclass of the other.

17. C. First off, the order of exceptions in a multi-catch does not matter, only that they notbe subclasses of one another, making Options A and B incorrect. Option C is thecorrect answer because a multi-catch variable is effectively final. Java forbidsreassigning of multi-catch variables since it is unclear what the precise reference typeis. Option D is incorrect because a multi-catch with a single exception type is just aregular catch block. A regular catch variable is not required to be effectively final andcan be reassigned within the catch block.

18. D. The code does not compile, so Option A is incorrect. The first compilation error isthat Shelf does not implement AutoCloseable, meaning a try-with-resourcesstatement cannot be used. Even though Shelf does implement Closing, an interfacethat uses the same abstract method signature as AutoCloseable, the JVM requiresAutoCloseable be implemented to use try-with-resources. The second compilationproblem is that throws is used instead of throw inside the try block. Remember thatthrows is only used in method signatures. The third compilation issue is that the orderof exceptions in the two catch blocks are reversed. Since Exception will catch allIllegalArgumentException instances, the second catch block is unreachable. The final

compilation error is that the shelf variable is used in the finally block, which is outof scope. Remember that the scope of try-with-resources variables ends when the trystatement is complete. For these four reasons, Option D is the correct answer.

19. A. Option A is the correct answer. Any catch or finally blocks used with a try-with-resources statement are executed after the declared resources have been closed, notbefore. Options B and C are true statements, since Closeable extends AutoCloseableand the requirement for try-with-resources is that they must be of type AutoCloseable.Finally, Option D is a true statement and one of the primary motivations for using try-with-resources statements.

20. D. The optional second parameter of an assert statement, when used, must return avalue. The second assert statement uses System.out.print() as its second parameter,which has a return type of void. For this reason, the code does not compile, makingOption D the correct answer. Other than this one line, the rest of the class compileswithout issue.

21. D. Only one of the classes, MissingResourceException, inherits from the uncheckedRuntimeException class, making Option D the correct answer. In fact, IOException andSQLException extend the checked Exception class directly. TheNotSerializableException is also checked, since it is a subclass of IOException viaObjectStreamException.

22. D. The code does not compile, making Options A and B incorrect. The declaration ofweatherTracker uses an anonymous inner class that correctly overrides the close()method. Remember that overridden methods cannot throw any new or broaderchecked exceptions than the inherited method. Alternatively, they can avoid throwinginherited checked exceptions or declare new unchecked exceptions, such asRuntimeException. The compilation error is in the catch block of the main() method,where the weatherTracker variable is out of scope. In try-with-resources statements,the resources are only accessible in the try block. For this reason, Option D is thecorrect answer.

23. A. Asserts can be enabled by using the command-line options -ea or -enableassertions and disabled by using -da or -disableassertions. Passing -di doesnot enable or disable assertions, making Option A the correct answer.

24. A. The application compiles without issue and prints Hello, making Option A thecorrect answer. The ReadSign and MakeSign classes are both correctly implemented,with both overridden versions of close() dropping the checked exception. The try-with-resources statement is also correctly implemented for two resources and doesnot cause any compilation errors or runtime exceptions. Note that the semicolon (;)after the second resource declaration is optional.

25. B. The code compiles, so Option D is incorrect. The order of evaluation for a try-with-resources statement is that the resources are closed before any associated catch orfinally blocks are executed. For this reason, 2 is printed first, followed by 1. The

ArithmeticException is then caught and 3 is printed. The last value printed is 4, sincethe finally block runs at the end. For these reasons, Option B is the correct answer.

26. B. First off, Option A is an incorrect statement because the AutoCloseable interfacedoes not define a default implementation of close(). Next, the close() methodshould be idempotent, which means it is able to be run multiple times withouttriggering any side effects. For this reason, Option B is correct. After being run once,future calls to close() should not change any data. Option C is incorrect because theclose() method is fully capable of throwing exceptions. In fact, the signature of themethod in AutoCloseable throws a checked Exception, although classes that overrideit may choose to drop the checked exception. Option D is incorrect because the returntype of close() is void, which means no return value can be returned.

27. D. The play() method compiles without issue, rethrowing a wrapped exception in thecatch block. While the main() method does declare RuntimeException, it does notdeclare or catch the Exception thrown by the calls to play(). Even though the play()method does not appear to actually throw an instance of Exception, because it isdeclared, the main() method must catch or declare it. Since the checked exception isnot handled, the main() method does not compile, and Option D is the correct answer.If the main() method was changed to declare the appropriate checked exception, thenthe rest of the code would compile, and exactly one exception would be printed,making Option A the correct answer.

28. B. Assertions are often used to check method post conditions, test control flowinvariants, and validate class invariants, making Options A, C, and D true statements.Option B is the correct answer. An assertion should never modify any data because itmay be disabled at runtime, leading to unintended side effects.

29. B. A multi-catch block cannot contain two exceptions in which one is a subclass of theother, since it is a redundant expression. Since CarCrash is a subclass ofRuntimeException and RuntimeException is a subclass of Exception, line w2 contains acompilation error, making Option B the correct answer. The rest of the lines of code donot contain any compilation errors.

30. B. First off, a class must inherit from RuntimeException or Error to be considered anunchecked exception. Dopey and Grumpy both are subclasses of Exception, but notRuntimeException, making them both checked exceptions. Since IOException is achecked exception, the subclass Happy is also a checked exception. Sleepy extendsIllegalStateException, which is an unchecked exception that extendsRuntimeException. Finally, Sneezy extends Throwable, which does not inheritRuntimeException or Error, making it a checked exception. Therefore, there are a totalof four checked exceptions and one unchecked exception within the classes listedhere. Since there are no compilation errors in any of the class declarations, Option B isthe correct answer, with the first and third statement being true.

31. D. The close() method in each of the resources throws an Exception, which must behandled or declared in the main() method. The catch block supports TimeException,

but it is too narrow to catch Exception. Since there are no other catch blocks presentand the main() method does not declare Exception, the try-with-resources statementdoes not compile, and Option D is the correct answer. If the catch block was modifiedto handle Exception instead of TimeException, the code would compile without issueand print 3215 at runtime, closing the resources in the reverse order in which theywere declared and making Option B the correct answer.

32. A. The try-catch block already catches Exception, so the correct answer would be theone that is not a subclass of Exception. In this case, Error extends Throwable and isthe only choice that allows the code to compile. Because IllegalStateException andRingException both inherit from Exception, Options B and C, respectively, areincorrect. Finally, Option D is incorrect because there is an answer choice that allowsthe code to compile.

33. B. Option A does not compile because the assignment (age=2) has a value of int, notboolean, which is required for an assert statement. Option B compiles without issueand is the correct answer. Even though Error and 10 are different data types, Stringand int respectively, the second assert parameter only needs to be a value, so bothare allowed. Option C does not compile because the usage of the lambda expressiondoes not match a functional interface. Option D is incorrect because a returnstatement is not allowed in the second expression of an assert statement.

34. D. The MissedCallException is a checked exception since it extends Exception anddoes not inherit RuntimeException. For this reason, the first catch block fails tocompile, since the compiler detects that it is not possible to throw this checkedexception inside the try block, making Option D the correct answer. Note that ifMissedCallException was changed to extend the checked RuntimeException, then thecode would compile and the RuntimeException from the finally block would replacethe ArrayIndexOutOfBoundsException from the try block in the message reported tothe caller, making Option C the correct answer.

35. D. The catch variable d is of type BearException that cannot be assigned an instance ofthe superclass RuntimeException without an explicit cast. For this reason, the firstcatch block does not compile in tellStory(). The second catch block also does notcompile, albeit for a slightly different reason. A catch variable in a multi-catch blockmust be effectively final because the precise type is not known until runtime.Therefore, the compiler does not allow the variable e to be reassigned. For these tworeasons, Option D is the correct answer. Note that the first catch block does allow thecatch variable d to be reassigned, it just must be to a class that inherits BearExceptionor is an instance of BearException.

36. D. The play() method declares two checked exceptions, OutOfTuneException andFileNotFoundException, which are handled in the main() method’s catch block usingthe Exception type. The catch block then rethrows the Exception. The compiler issmart enough to know that only two possible checked exceptions can be thrown here,but they both must be handled or declared. Since the main() method only declares one

of the two checked exceptions, FileNotFoundException is not handled, and the codedoes not compile. For this reason, Option D is the correct answer. Note that the main()could have also handled or declared Exception, since both checked exceptions inheritit. If the main() method had declared Exception, then Song finished! would havebeen printed followed by a stack trace, making Option C the correct answer.

37. C. The code compiles without issue, making Option D incorrect. Option A is incorrectbecause assertions are not enabled by default in Java. Therefore, the code will runwithout throwing any exceptions. Option B is also incorrect because the commandenables assertions everywhere but disables them for the Falcon class. Option C is thecorrect answer, with the command disabling assertions everywhere except in theFalcon class, causing an AssertionError to be thrown at runtime.

38. C. The Closeable interface defines a close() method that throws IOException. Theoverridden implementation of MyDatabase, which implements Closeable, declares aSQLException. This is a new checked exception not found in the inherited methodsignature. Therefore, the method override is invalid and the close() method inMyDatabase does not compile, making Option C the correct answer.

39. D. The code does not compile because the close() method throws an Exception that isnot handled or declared in the main() method, making Option D the correct answer.When a try-with-resources statement is used with a close() method that throws achecked exception, it must be handled by the method or caught within the try-with-resources statement.

40. B. The code compiles without issue, making Option C incorrect. In the climb()method, two exceptions are thrown. One is thrown by the close() method and theother by the try block. The exception thrown in the try block is considered theprimary exception and reported to the caller on line e1, while the exception thrown bythe close() method is suppressed. For this reason, java.lang.RuntimeException isthrown to the main() method, and Option B is the correct answer.

Chapter 17: Use Java SE 8 Date/Time API1. C. The date and time classes added in Java 8 are in the java.time package, making

Option C correct. The older date classes are in the java.util package.

2. A. The Duration class is used to reflect an amount of time using small units likeminutes. Since it just uses units of time, it does not involve time zones. The LocalTimeclass contains units of hours, minutes, seconds, and fractional seconds. TheLocalDateTime class contains all the data in a LocalTime and adds on a year, month,and date. Neither of these classes uses time zones. There is a ZonedDateTime classwhen you need to use time zones. Since none of the three classes listed includes atime zone, Option A is correct.

3. A. A Period is measured in days, weeks, months, or years. A Duration is measured insmaller units like minutes or seconds. Only Duration has a getSeconds() method,making Option A correct.

4. D. To compare times in different time zones, you can subtract the time zone from thetime to convert to GMT. This makes it 02:00 in Berlin because we subtract 1 from 3.Similarly, it is 02:00 in Helsinki due to subtracting 2 from 4. Finally, it is 04:00 inWarsaw because we subtracted 1 from 5. We have a tie because it is the same time inBerlin and Helsinki, so Option D is correct.

5. B. On a normal night, adding three hours to 1 a.m. makes it 4 a.m. However, this datebegins daylight savings time. This means we add an extra hour to skip the 2 a.m. hour.This makes later contain 05:00 instead of 04:00. Therefore, the code prints 5, andOption B is correct.

6. C. LocalDate allows passing the month as an int or Month enum parameter. However,Month.MARCH is an enum. It cannot be assigned to an int variable, so the declaration ofmonth does not compile, and Option C is correct.

7. C. Both LocalDate and DateTimeFormatter have a format() method. This makes IIincorrect. While it is tricky, you do need to know that the format() method can becalled on either object. Since I and III are correct, Option C is the answer.

8. C. Converting to GMT by subtracting the time zone offset, it is 17:00 for the Phoenixtime since 10 minus negative 7 is 17. In GMT, the Vancouver time is 16:00 due tosubtracting negative 8 from 8. Remember that subtracting a negative number is thesame as adding. Therefore, the Vancouver time is an hour earlier than the Phoenixtime, and Option C is correct.

9. C. While there is no 2 a.m. on the clock that night, Java adjusts the time to 3 a.m.automatically and changes the time zone. It does not throw an exception, so Option Dis incorrect. Option B is a valid expression, since any value after the time adjustmentis just a normal time on the clock. Since both A and B are valid expressions, Option Cis the correct answer.

10. B. Line 12 creates a Period representing a year, six months, and three days. Adding thisto waffleDay gives us the year 2018, the month of September, and a day of 28. Thisnew date is stored in later on line 13 and represents September 28, 2018. Line 14 hasno effect as the return value is ignored. Line 17 checks that you know that isBefore()returns false if the value is an exact match. Since thisOne is an exact match butthatOne is a whole day before, the output is false true, making Option B correct.

11. D. Duration is supposed to be used with objects that contain times. While it has anofDays() method, this is a convenience method to represent a large number ofseconds. This means that calling Duration.ofDays(1) is fine. However, this codethrows an UnsupportedTemporalTypeException when you try to pass it the minus()method on LocalDate, making Option D correct. Note that the question asks about apossible result rather than the definitive result because the format of dates varies byregion.

12. C. The DateTimeFormatter is created with ofLocalizedDate(). It knows how to formatdate fields but not time fields. Line 18 is fine because a LocalDate clearly has datefields. Line 19 is also fine. Since a LocalDateTime has both date and time fields, theformatter just looks at the date fields. Line 20 is a problem. A LocalTime object doesnot have any date fields so the formatter throws anUnsupportedTemporalTypeException, making Option C the answer.

13. D. This question is tricky. It appears to be about daylight savings time. However, theresult of z.plusHours(1) is never stored in a variable or used. Since ZonedDateTime isimmutable, the time remains at 01:00. The code prints out 1, making none of thesecorrect and Option D the answer.

14. D. For dates, a lowercase m means minute while an uppercase M means month. Thiseliminates Options A and C. A lowercase h means hour. Therefore, Option B isincorrect, and Option D is the answer.

15. D. There are three overloads for LocalTime.of(). Options A, B, and C are all validoverloads. Option D is not because Java only allows passing one fractional secondparameter. Java does support nanoseconds, but not the further granularity ofpicoseconds.

16. C. The LocalDate class represents a date using year, month, and day fields. There is agetYear() method to get the year. The Period class holds units of years, months, anddays. It has a getYears() method. There is not a date/time class called ZonedDate.There is a class called ZonedDateTime, which does have a getYear() method. Since onlyLocalDate and Period have a method to get the year, Option C is correct.

17. A. Duration is used for units of time a day and smaller, making Option B a truestatement. Period is used for units of time a day and larger, making Option C a truestatement. While both represent the same length of time, they output different valueswhen calling toString(). The Duration object outputs PT24H, and the Period objectoutputs P1D. This shows that Duration is providing the ofDays() method as a

convenience instead of requiring the programmer to type 24 hours. Option A is theanswer.

18. B. The first thing to notice is that this is a LocalTime object. Since there is no datecomponent, Options C and D are incorrect. Four parameters are passed to thisLocalTime method. The first three are the hour, minute, and second. The fourth isnanoseconds, which are fractions of a second. While you aren’t expected to docalculations with nanoseconds, you should know that a fraction of a second is at theend of the output. Option A is incorrect because .4 is 40 percent of a second. That’s farlarger than 4 nanoseconds. Therefore, Option B is correct.

19. B. LocalDate starts counting months from one, so month 2 is February. This rules outOptions A and C. The pattern specifies that the date should appear before the month,making Option B correct.

20. A. The ChronoUnit enum contains values for various measures of time including HOURS,so Option A is correct.

21. B. Adding three hours to 13:00 makes it 16:00. While this date happens to be the startof daylight savings time, the change occurs at 2 a.m. This code uses 13:00, which is 1p.m. Since the calculation does not cross 2 a.m., the fact that it is the date that startsdaylight savings time is irrelevant. Option B is correct because the hour is 16 and thetime is 16:00.

22. B. This code correctly subtracts a day from montyPythonDay. It then outputs aLocalDateTime value. Option A is incorrect because it omits the time. Option B iscorrect because it represents one day earlier than the original date and includes a timein the output.

23. D. There is a DateTimeFormatter class, but not a DateFormatter class. TheDateTimeFormatter class is used for formatting dates, times, or both. Since theprovided code does not compile, nothing can fill in the blank to make the code print2017-01-15, and Option D is the answer.

24. B. There are many overloads for LocalDateTime.of(). Option A is a valid overloadbecause it uses date and time objects. Options C and D are also valid overloads,showing you can pass the month as an int or Month enum. Option B is the answer. Javadoesn’t allow combining a LocalDate object with time fields directly.

25. C. In the first time change of the year, clocks “spring ahead” and skip the 02:00–03:00hour entirely. This means 1:59 is followed by 03:00 on March 12, 2017. By contrast,July 4 is a normal day and 1:59 is followed by 02:00. In the second time change of theyear, clocks “fall back” and repeat an hour, so 1:59 is followed by 01:00. Granted, youcan’t tell whether this is the first or second 1:59 from the image. If this information isrelevant to a question’s context, the question will specify this fact. In this case, 03:00,02:00, 02:00 is not a choice. Option C is the answer.

26. D. February has 28 or 29 days, depending on the year. There is never a February 31.

Java throws a DateTimeException when you try to create an invalid date, makingOption D correct.

27. A. This one is tricky. In order to determine GMT, you need to subtract the time zoneoffset from the hour. In this case, the time zone offset is negative 10. Since subtractinga negative number is like adding a positive number, this means we are adding 16 and10. That gives us 26. However, there are only 24 hours in a day. We’ve crossed a timezone boundary, so we can remove a whole 24-hour day. Subtracting 24 from 26 givesus 2. This means it is 02:00 in GMT, and Option A is correct. It’s also a day later inGMT, but the question didn’t ask that.

28. D. An Instant represents a specific moment in time using GMT. Since there are notime zones included, Options A and C are incorrect. This code correctly adds one day tothe instant, making Option D correct.

29. D. Make sure to pay attention to date types. This code attempts to add a month to aLocalTime value. There is no plusMonths() method on LocalTime, so Option D iscorrect.

30. D. The format of the pattern is incorrect. You can’t just put literal text in there. Mostof the characters of Holiday: are not defined formatting symbols. The code throws anIllegalArgumentException, so Option D is correct.

31. A. To compare times in different time zones, you can subtract the time zone from thetime. This makes it 09:00 in Bangkok because we subtract 7 from 16. Similarly, it is14:00 in Dubai due to subtracting 4 from 18. Finally, it is 12:00 in Kuala Lumpurbecause we subtracted 8 from 20. Notice how we used a 24-hour clock to makecomparing times easier. The earliest time is in Bangkok, so Option A is correct.

32. C. Line 12 creates a Period representing three days. Period objects do not chain, soonly the last method call, which is to ofDays(3), is used in determining the value.Adding three days sets later to March 28, 2017. Line 14 has no effect as the returnvalue is ignored. March 28, 2017, is before both thisOne and thatOne, so Option C iscorrect.

33. B. The TemporalUnit interface does not define a DAYS constant, making II and IVincorrect. The until() and between() methods have the same behavior. Theydetermine how many units of time are between two dates. One takes both dates asparameter and the other is an instance method on the date. Since I and III areequivalent, Option B is the answer. Note that while we don’t have date times in thisquestion, the until() and between() methods work the same way for them.

34. A. The DateTimeFormatter class is used to format all of these objects. The method willthrow an exception if called with a LocalDate since the formatter only knows abouttime fields. However, it will still compile, making Option A correct.

35. B. This code begins by correctly creating four objects. It then adds a month to date.Since Java 8 date/time classes are immutable, this does not affect the value of

iceCreamDay. Therefore, iceCreamDay remains in July. Since months count from one,Option B is correct.

36. A. Java 8 date and time classes are immutable. They use a static factory method toget the object reference rather than a constructor. This makes Options B and Dincorrect. Further, there is not a ZonedDate class. There is a ZonedDateTime class. As aresult, Option C is incorrect, and Option A is the answer.

37. B. The first line of code correctly creates a LocalDate object representing March 3,2017. The second line adds two days to it, making it March 5. It then subtracts a day,making it March 4. Finally, it subtracts yet another day ending at March 3. Theoutcome of all this is that we have two dates that have the same value, and Option B iscorrect.

38. C. An Instant represents a specific moment in time using GMT. Since LocalDateTimedoes not have a time zone, it cannot be converted to a specific moment in time.Therefore, the toInstant() call does not compile, and Option C is correct.

39. A. While it is traditional to include the year when outputting a date, it is not required.This code correctly prints the month followed by a decimal point. After the decimalpoint, it prints the day of the month followed by the hours and minutes. Happy PiDay!

40. C. Normally, adding an hour would result in 02:00 in the same time zone offset of –05:00. Since the hour is repeated, it is 01:00 again. However, the time zone offsetchanges instead. Therefore, Option C is correct.

Chapter 18: Java I/O Fundamentals1. B. Writer is an abstract class, making Option B the correct answer. Note that

InputStream, OutputStream, and Reader are also abstract classes.

2. D. File uses mkdir() and mkdirs() to create a directory, not createDirectory(),making Option A incorrect. Note there is a createDirectory() method in the NIO.2Files class. The getLength() method also does not exist, as the correct method iscalled length(). Next, there is a listFiles() method used to read the contents of adirectory, but there is no listFile() method. That leaves us with renameTo(), whichdoes exist and is used to rename file system paths.

3. C. The skip() method just reads a single byte and discards the value. The read()method can be used for a similar purpose, making Option C the correct answer. OptionA is incorrect because there is no jump() method defined in InputStream. Options Band D are incorrect because they cannot be used to skip data, only to mark a locationand return to it later, respectively.

4. D. Serializable is a marker or tagging interface, which means it does not contain anymethods and is used to provide information about an object at runtime. Therefore,Option D is the correct answer because the interface does not define any abstractmethods.

5. C. Given a valid instance of Console, reader() returns an instance of Reader, whilewriter() returns an instance of PrintWriter. Reader and PrintWriter was not ananswer choice though, making Option C the next best choice since PrintWriterinherits Writer. Options A and B are incorrect because PrintReader is not defined inthe java .io library. Option D is incorrect because the type of the instance returnedby reader() is Reader, which does not inherit StringReader.

6. D. BufferedWriter is a wrapper class that requires an instance of Writer to operate on.In the Smoke class, a FileOutputStream is passed, which does not inherit Writer,causing the class not to compile, and making Option D the correct answer. IfFileWriter was used instead of FileOutputStream, the code would compile withoutissue and print 13, making Option B the correct answer.

7. A. The File class is used to read both files and directories within a file system, makingOption A the correct answer. The other three classes do not exist. Note there is anNIO.2 interface, java.nio.file.Path, used to read both file and path information.

8. C. FileOutputStream and FileReader are both low-level streams that operate directlyon files, making Options A and B incorrect. ObjectInputStream is a high-level streamthat can only wrap an existing InputStream. For this reason, Option C is the correctanswer. PrintWriter can operate on other streams, but it can also operate on files.Since the question asks which class can only wrap low-level streams, Option D isincorrect.

9. D. The code compiles, so Option C is incorrect. The FileInputStream does not support

marks, though, leading to an IOException at runtime when the reset() method iscalled. For this reason, Option D is the correct answer. Be suspicious of any codesamples that call the mark() or reset() method without first calling markSupported().

10. C. The absolute path is the full path from the root directory to the file, while therelative path is the path from the current working directory to the file. For this reason,Option C is the correct answer.

11. D. The difference between the two methods is that writeSecret1() does not take anysteps to ensure the close() method is called after the resource is allocated. On theother hand, writeSecret2() uses a try-with-resources block, which automatically triesto close the resource after it is used. Without a try-with-resources statement or anequivalent finally block, any exception thrown by the write() method would causethe resource not to be closed in the writeSecret1() method, possibly leading to aresource leak. For this reason, Option D is the correct answer. Option A is incorrectsince they are not equivalent to each other. Finally, Options B and C are incorrectbecause both compile without issue.

12. A. The constructor for Console is private. Therefore, attempting to call new Console()outside the class results in a compilation error, making Option A the correct answer.The correct way to obtain a Console instance is to call System.console(). Even if thecorrect way of obtaining a Console had been used, and the Console was available atruntime, stuff is null in the printItinerary() method. Referencingstuff.activities results in a NullPointerException, which would make Option B thecorrect answer.

13. A. While you might not be familiar with FilterOutputStream, the diagram shows thatthe two classes must inherit from OutputStream. Options B and C can be eliminated aschoices since PrintOutputStream and Stream are not the name of any java.io classes.Option D can also be eliminated because OutputStream is already in the diagram, andyou cannot have a circular class dependency. That leaves us with the correct answer,Option A, with BufferedOutputStream and PrintStream both extendingFilterOutputStream. Note that ByteArrayOutputStream and FileOutputStreamreferenced in Options C and D, respectively, do not extend FilterOutputStream,although knowing this fact was not required to solve the problem.

14. D. The Cereal class does not implement the Serializable interface; therefore,attempting to write the instance to disk, or calling readObject() usingObjectInputStream, will result in a NotSerializableException at runtime. For thisreason, Option D is the correct answer. If the class did implement Serializable, thenthe value of name would be CornLoops, since none of the constructor, initializers, orsetters methods are used on deserialization, making Option B the correct answer.

15. B. An OutputStream is used to write bytes, while a Writer is used to write characterdata. Both can write character data, the OutputStream just needs the data converted tobytes first. For this reason, Option A is incorrect. Option B is the correct answer, withWriter containing numerous methods for writing character or String data. Both

interfaces contain a flush() method, making Option C incorrect. Finally, because bothcan be used with a byte array, Option D is incorrect.

16. C. First off, the code compiles without issue. The first method call to mkdirs() createstwo directories, /templates and /templates/proofs. The next mkdir() call isunnecessary, since /templates/proofs already exists. That said, calling it on anexisting directory is harmless and does not cause an exception to be thrown atruntime. Next, a file draft.doc is created in the /templates directory. The final twolines attempt to remove the newly created directories. The first call to delete() issuccessful because /templates/proofs is an empty directory. On the other hand, thesecond call to delete() fails to delete the directory /templates because it is non-empty, containing the file draft.doc. Neither of these calls trigger an exception atruntime, though, with delete() just returning a boolean value indicating whether thecall was successful. Therefore, our program ends without throwing any exceptions,and Option C is the correct answer.

17. D. To answer the question, you need to identify three of the four ways to call thesystem-independent file name separator. For example, the file name separator is oftena forward-slash (/) in Linux-based systems and a backward-slash (\) in Windows-based systems. Option A is valid because it is the fully qualified name of the property.Option B is also valid because File.separator and File.separatorChar are equivalent.While accessing a static variable using an instance is discouraged, as shown inOption B, it is allowed. Option C is valid and a common way to read the characterusing the System class. Finally, Option D is the correct answer and one call that cannotbe used to get the system-dependent name separator character. Note thatSystem.getProperty("path.separator") is used to separate sets of paths, not nameswithin a single path.

18. D. The first compilation error is that the FileReader constructor call is missing the newkeyword. The second compilation error is that the music variable is marked final, butthen modified in the while loop. The third compilation problem is that thereadMusic() method fails to declare or handle an IOException. Even though theIOException thrown by readLine() is caught, the one thrown by the implicit call toclose() via the try-with-resources block is not caught. Due to these three compilationerrors, Option D is the correct answer.

19. C. Both of the methods do exist, making Option D incorrect. Both methods take thesame arguments and do the exact same thing, making Option C the correct answer.The printf() was added as a convenience method, since many other languages useprintf() to accomplish the same task as format().

20. C. FileWriter and BufferedWriter can be used in conjunction to write large amountsof text data to a file in an efficient manner, making Option C the correct answer. Whileyou can write text data using FileOutputStream and BufferedOutputStream, they areprimarily used for binary data. Since there is a better choice available, Option A isincorrect. Option B is incorrect since FileOutputWriter and FileBufferedWriter are

not classes that exist within the java.io API. Option D is incorrect sinceObjectOutputStream is a high-level binary stream. Also, while it can write String data,it writes it in a binary format, not a text format.

21. D. The code compiles and runs without issue, so Options A and B are incorrect. Theproblem with the implementation is that checking if ios.readObject() is null is notthe recommended way of iterating over an entire file. For example, the file could havebeen written with writeObject(null) in-between two non-null records. In this case,the reading of the file would stop on this null value, before the end of the file hasbeen reached. For this reason, Option D is the correct answer. Note that the valid wayto iterate over all elements of a file using ObjectInputStream is to continue to callreadObject() until an EOFException is thrown.

22. D. BufferedInputStream is the complement of BufferedOutputStream. Likewise,BufferedReader and FileReader are the complements of BufferedWriter andFileWriter, respectively. On the other hand, PrintWriter does not have anaccompanying PrintReader class within the java.io API, making Option D the correctanswer. Remember that this is also true of PrintStream, as there is noPrintInputStream class.

23. C. The File getParent() method returns a String, not a File object. For this reason,the code does not compile on the last line since there is no getParent() methoddefined in the String class, and Option C is correct. If the first method call on the lastline was changed to getParentFile(), then the code would compile and run withoutissue, outputting / - null and making Option B the correct answer. The File classdoes not require the location to exist within the file system in order to perform someoperations, like getParent(), on the path.

24. D. All three statements about the program are correct. If System.console() isavailable, then the program will ask the user a question and then print the response ifone is entered. On the other hand, if System.console() is not available, then theprogram will exit with a NullPointerException. It is strongly recommended to alwayscheck whether or not System.console() is null after requesting it. Finally, the usermay choose not to respond to the program’s request for input, resulting in theprogram hanging indefinitely and making the last statement true.

25. C. The code contains two compilation errors. First, the File list() method returns alist of String values, not File values, so the call to deleteTree() with a String valuedoes not compile. Either the call would have to be changed to f.listFiles() or thelambda expression body would have to be updated to deleteTree(new File(s)) for thecode to work properly. Next, there is no deleteDirectory() method in the File class.Directories are deleted with the same delete() method used for files, once they havebeen emptied. With those two sets of corrections, the method would compile and becapable of deleting a directory tree. Notice we continually used the phrase “capable ofdeleting a directory tree.” While the corrected code is able to delete a directory tree, itmay fail in some cases, such as if the file system is read-only.

26. C. System.err, System.in, and System.out are each valid streams defined in the Systemclass. System.info is not, making Option C the correct answer.

27. D. The code compiles without issue, making Options B and C incorrect. TheBufferedWriter uses the existing FileWriter object as the low-level stream to writethe file to disk. By using the try-with-resources block, though, the BufferedWritercalls close() before executing any associated catch or finally blocks. Since closing ahigh-level stream automatically closes the associated low-level stream, the w object isalready closed by the time the finally block is executed. For this reason, the flush()command triggers an IOException at runtime, making Option D the correct answer.Note that the call to w.close(), if that line was reached, does not trigger an exception,because calling close() on already closed streams is innocuous.

28. B. The Console class contains a reader() method that returns a Reader object. TheReader class defines a read() method, but not a readLine() method. For this reason,Option B is the correct answer. Recall that a BufferedReader is required to call thereadLine() method. Options A, C, and D are valid ways to read input from the user.

29. C. The code compiles without issue, since InputStream and OutputStream both supportreading/writing byte arrays, making Option A incorrect. Option D is also incorrect.While it is often recommended that an I/O array be a power of 2 for performancereasons, it is not required, making Option D incorrect. This leaves us with Options Band C. The key here is the write() method used does not take a length value, availablein the chirps variable, when writing the file. The method will always write the entiredata array, even when only a handful of bytes were read into the data array, whichmay occur during the last iteration of the loop. The result is that files whose bytes area multiple of 123 will be written correctly, while all other files will be written withextra data appended to the end of the file. For this reason, Option C is the correctanswer. If the write(data) call was replaced with write(data,0,chirps), which doestake the number of bytes read into consideration, then all files would copy correctly,making Option B the correct answer.

30. C. The class name has three components that tell you what it would do if it was ajava.io stream. First, Buffered tells you it can be used to handle large data setsefficiently. Next, File tells you it is involved in reading or writing files. Finally, Readertells you it is used to read character data. Therefore, the class would be useful forreading large files of character data from disk efficiently, making Option C the correctanswer. Option A is incorrect because it refers to a small file over a network. Options Band D are incorrect because both involve binary data.

31. A. The code compiles and runs without issue. The first two values of theByteArrayInputStream are read. Next, the markSupported() value is tested. Since -1 isnot one of the possible answers, we assume that ByteArrayInputStream does supportmarks. Two values are read and three are skipped, but then reset() is called, puttingthe stream back in the state before mark() was called. In other words, everythingbetween mark() and reset() can be ignored. The last value read is 3, making Option A

the correct answer.

32. C. Line 5 creates a File object, but that does not create a file in the file system unlesscake.createNewFile() is called. Line 6 also does not necessarily create a file, althoughthe call to flush() will on line 7. Note that this class does not properly close the fileresource, potentially leading to a resource leak. Line 8 creates a new File object,which is used to create a new directory using the mkdirs() method. Recall from yourstudies that mkdirs() is similar to mkdir(), except that it creates any missingdirectories in the path. Since directories can have periods (.) in their name, such as adirectory called info.txt, this code compiles and runs without issue. Since two filesystem objects, a file and a directory, are created, Option C is the correct answer.

33. B. Since the file is stored on disk, FileInputStream is an appropriate choice. Next,because the data is quite large, a BufferedInputStream would help improve access.Finally, since the data is a set of Java values, ObjectInputStream would allow variousdifferent formats to be read. The only one that does not help in this process isBufferedReader, Option B. BufferedReader should be used with text-based Readerstreams, not binary InputStream objects.

34. B. The flush() method is defined on classes that inherit Writer and OutputStream, notReader and InputStream. For this reason, the r.flush() in both methods does notcompile, making Option B the correct answer and Option C incorrect. The methods arenot equivalent even if they did compile, since getNameSafely() ensures the resource isclosed properly by using a try-with-resources statement, making Option A incorrectfor two reasons. Finally, Option D would be correct if the calls to flush() wereremoved.

35. A. First off, the class compiles without issue. Although there are built-in methods toprint a String and read a line of input, the developer has chosen not to use them formost of the application. The application first prints Pass, one character at a time. Theflush() method does not throw an exception at runtime. In fact, it helps make surethe message is presented to the user. Next, the user enters badxbad and presses Enter.The stream stops reading on the x, so the value stored in the StringBuilder is bad.Finally, this value is printed to the user, using the format() method along withResult: as a prefix. For these reasons, Option A is the correct answer.

36. B. The readPassword() returns a char array for security reasons. If the data was storedas a String, it would enter the shared JVM string pool, potentially allowing amalicious user to access it, especially if there is a memory dump. By using a chararray, the data can be immediately cleared after it is written and removed frommemory. For this reason, Option B is the correct answer. The rest of the statementsare not true.

37. A. The BufferedInputStream constructor in the readBook() method requires anInputStream as input. Since FileReader does not inherit InputStream, the readBook()method does not compile, and Option A is the correct answer. If FileReader waschanged to FileInputStream, then the code would compile without issue. Since read()

is called twice per loop iteration, the program would print every other byte, makingOption C correct. Remember that InputStream read() returns -1 when the end of thestream is met. Alternatively, we use EOFException with ObjectInputStreamreadObject() to determine when the end of the file has been reached.

38. B. Generally speaking, classes should be marked with the Serializable interface ifthey contain data that we might want to save and retrieve later. Options A, C, and Ddescribe the type of data that we would want to store over a long period of time.Option B, though, defines a class that manages transient or short-lived data.Application processes change quite frequently, and trying to reconstruct a process isoften considered a bad idea. For these reasons, Option B is the best answer.

39. D. The receiveText() method compiles and runs without issue. The method correctlychecks that the mark() method is supported before attempting to use it. Based on theimplementation with reset(), the pointer is in the same location before/after the if-then statement. On the other hand, the sendText() method does not compile. Theskip() method is defined on InputStream and Reader, not OutputStream and Writer,making Option D the correct answer. If this line was removed, the rest of the codewould compile and run without issue, printing You up? at runtime and making OptionA the correct answer.

40. B. The class compiles and runs without issue, so Option D is incorrect. The classdefines three variables, only one of which is serializable. The first variable, chambers,is serializable, with the value 2 being written to disk and then read from disk. Notethat constructors and instance initializers are not executed when a class isdeserialized. The next variable, size, is transient. It is discarded when it is written todisk, so it has the default object value ofnull when read from disk. Finally, thevariable color is static, which means it is shared by all instances of the class. Eventhough the value was RED when the instance was serialized, this value was not writtento disk, since it was not part of the instance. The constructor call new Value() betweenthe two try-with-resources blocks sets this value to BLUE, which is the value printedlater in the application. For these reasons, the class prints 2,null,BLUE, makingOption B the correct answer.

Chapter 19: Java File I/O (NIO.2)1. C. A symbolic link is a file that contains a reference to another file or directory within

the file system, making Options A and B incorrect. Further, there is no such thing asan irregular file. Option C is the correct answer because a regular file is not a directoryand contains content, unlike a symbolic link or resource. Option D is also incorrectbecause all symbolic links are stored as files, not directories, even when their target isa directory.

2. C. The NIO.2 Path interface contains the methods getRoot() and toRealPath(). On theother hand, the method isDirectory() is found in the NIO.2 Files class, while themethod listFiles() is found in the java.io.File class. For these reasons, Option C isthe correct answer.

3. A. The code does not compile because there is no NIO.2 class File that contains anisHidden() method, making Option A the correct answer. There is a java.io.Fileclass, but that does not contain an isHidden() method either. The correct call isFiles.isHidden(). Remember to check File vs. Files as well as Path vs. Paths on thereal exam. If the correct method call was used, the program would print Found!, andOption C would be the correct answer.

4. D. A breadth-first traversal is when all elements of the same level, or distance fromthe starting path, are visited before moving on to the next level. On the other hand, adepth-first traversal is when each element’s entire path, from start to finish, is visitedbefore moving onto another path on the same level. Both walk() and find() usedepth-first traversals, so Option D is the correct answer.

5. A. Reading an attribute interface is accomplished in a single trip to the underlying filesystem. On the other hand, reading multiple file attributes using individual Filesmethods requires a round-trip to the file system for each method call. For thesereasons, Option A is the correct answer. Option B is incorrect because nothingguarantees it will perform faster, especially if the Files method is only being used toread a single attribute. For multiple calls, it is expected to be faster, but the statementuses the word guarantees, which is incorrect. Option C is also incorrect because bothhave built-in support for symbolic links. Finally, Option D is incorrect because thisdiscussion has nothing to do with memory leaks.

6. B. First off, the class compiles without issue. It is not without problems, though. TheFiles.isSameFile() method call on line j1 first checks if the Path values areequivalent in terms of equals(). One is absolute and the other is relative, so this testwill fail. The isSameFile() method then moves on to verify that the two Path valuesreference the same file system object. Since we know the directory does not exist, thecall to isSameFile() on line j1 will produce a NoSuchFileException at runtime, makingOption B the correct answer.

7. B. A cycle is caused when a path contains a symbolic link that references the pathitself, or a parent of the parent, triggering an infinitely deep traversal. That said,

Files.walk() does not follow symbolic links by default. For this reason, the cycle isnever activated, and the code would print a number at runtime, making Option B thecorrect answer. If the FOLLOW_LINKS enum value was used in the call to Files.walk(),then it would trigger a cycle resulting in a FileSystemLoopException at runtime, andOption A would be the correct answer.

8. B. The methods length() and getLength() do not exist in the Files class, makingOptions A and C incorrect. Recall that the java.io.File method retrieves the size of afile on disk. The NIO.2 Files class includes the Files.size() method to accomplishthis same function. For this reason, Option B is the correct answer.

9. D. The code compiles without issue, making Option C incorrect. Even though trickswould be dropped in the normalized path /bag/of/disappear.txt, there is nonormalize() call, so path.subpath(2,3) returns tricks on line 5. On line 6, the call togetName() throws an IllegalArgumentException at runtime. Since getName() is zero-indexed and contains only one element, the call on line 6 throws anIllegalArgumentException, making Option D the correct answer. If getName(0) hadbeen used instead of getName(1), then the program would run without issue and print/home/tricks, and Option A would have been the correct answer.

10. A. The NIO.2 Files class contains the method isSameFile(). The methods length()and mkdir() are found in java.io.File, with the NIO.2 equivalent versions beingFiles.size() and Files.createDirectory(), respectively. In addition, therelativize() method is found in NIO.2 Path, not Files. Since only isSameFile() isfound in NIO.2 Files, Option A is the correct answer.

11. B. First off, the code compiles without issue, so Option D is incorrect. The enum valueREPLACE_EXISTING does not use a type, although this compiles correctly if a staticimport of StandardCopyOption is used. The AtomicMoveNotSupportedException inOption A is only possible when the ATOMIC_MOVE option is passed to the move()method. Similarly, the FileAlreadyExistsException in Option C is only possible whenthe REPLACE_EXISTING option is not passed to the move() method. That leaves us withthe correct answer of Option B. A DirectoryNotEmptyException can occur regardless ofthe options passed to the Files.move() method.

12. D. The Path method getFileName() returns a Path instance, not a String. For thisreason, the code does not compile, regardless of which line of code is inserted into theblank, making Option D the correct answer. Statements I and III are two valid ways tocreate a Path instance. If the method was updated to use Path as the return type, thenOption B would be the correct answer. Statement II would cause the method to notcompile, because Path is an interface and requires a class to be instantiated.

13. A. The code compiles without issue, but that’s about it. The class may throw anexception at runtime, since we have not said whether or not the source file exists norwhether the target file already exists, is a directory, or is write-protected. For thesereason, Option B is incorrect. Option C is also incorrect because the implementation isa flawed copy method. On a regular file, the code will copy the contents but the line

breaks would be missing in the target file. In order to correctly copy the original file, aline break would have to be written after each time temp is written. Since it is the onlycorrect statement, Option A is the correct answer.

14. C. First off, there is no Files.readLines() method, making Options B and Dimmediately incorrect. The Files.readAllLines() method returns a List<String>,while the Files.lines() method returns a Stream<String>. For this reason, Option Cis the correct answer, and Option A is incorrect.

15. A. The program compiles and runs without issue, making Options C and D incorrect.Like String instances, Path instances are immutable. For this reason, the resolve()operation on line 7 has no impact on the lessTraveled variable. Since one Path endswith /spot.txt and the other does not, they are not equivalent in terms of equals(),making Option A the correct answer. If lines 6 and 7 were combined, such that theresult of the resolve() operation was stored in the lessTraveled variable, thennormalize() would reduce lessTraveled to a Path value that is equivalent tooftenTraveled, making Option B the correct answer.

16. C. Options A, B, and D are each advantages of using NIO.2. As you may remember,using an attribute view to read multiple attributes at once is more efficient than asingle attribute call since it involves fewer round trips to the file system. Option C isthe correct answer. Neither API provides a single method to delete a directory tree.

17. C. The Files.delete() method has a return type of void, not boolean, resulting in acompilation error and making Option C the correct answer. There is another method,Files.deleteIfExists(), which returns true if the file is able to be deleted. If it wasused here instead, the file would compile and print a list of true values, makingOption A the correct answer. As stated in the description, the directory tree is fullyaccessible, so none of the Files.deleteIfExists() would return false.

18. D. First off, DosFileAttributes and PosixFileAttributes extendBasicFileAttributes, which means they are compatible with the readAttributes()method signature. Second, they produce instances that inherit the interfaceBasicFileAttributes, which means they can be assigned to a variable b of typeBasicFileAttributes without an explicit cast. For this reason, all three interfaces arepermitted, and Option D is the correct answer.

19. D. The relativize() method requires that both path values be absolute or relative.Based on the details provided, p1 is a relative path, while p2 is an absolute path. Forthis reason, the code snippet produces an exception at runtime, making Option D thecorrect answer. If the first path was modified to be absolute by dropping the leadingdot (.) in the path expression, then the output would match the values in Option A.

20. C. First off, p2 is an absolute path, which means that p1.resolve(p2) just returns p2.For this reason, Option B is incorrect. Since p1 is a relative path, it is appended ontop2, making Option C correct and Option A incorrect.

21. B. The code does not compile because Files.list() returns a Stream<Path>, not a

List<Path>, making Option B the correct answer. Note that java.io.File does includea list() method that returns an array of String values and a listFiles() method thatreturns an array of File values, but neither is applicable here.

22. C. For this problem, remember that the path symbols can be applied to simplify thepath before needing to apply any symbolic links in the file system. The paths inOptions A and B can both be reduced from/objC/bin/../backwards/../forward/Sort.java and/objC/bin/../forward/./Sort.java, respectively, to /objC/forward/Sort.java justusing the path symbols. Because of the symbolic link, this references the same file as/java/Sort.java. For these reasons, Options A and B match our target path. Option Ccan be reduced from /objC/bin/../java/./forward/Sort.java to/objC/java/forward/Sort.java, which does not match the desired path for the file.The symbolic link is not followed since it exists in the /objC directory, not in the/objC/java directory. This causes a stack trace to be printed at runtime since the pathdoes not exist, making Option C the correct answer. Option D can be reduced from/objC/bin/../../java/Sort.java to /java/Sort.java, which matches the target pathwithout using the symbolic link.

23. B. We need to empty the /objC directory before we can delete it. First, the Heap.exefile would have to be deleted before the bin directory could be removed, for a total oftwo calls to Files.delete(). Next, the Heap.m file is easily deleted with a single call toFiles.delete(). Calling Files.delete() on the symbolic link forward deletes the linkitself and leaves the target of the symbolic link intact. With a total of four calls, OptionB is the correct answer. Option A is incorrect because Java requires directories to beempty before they can be deleted. Option C is also incorrect. It might make sense ifFiles.delete() traversed symbolic links on a delete, but since this is not the case, it isan incorrect answer. Option D is incorrect because there is noFiles.deleteSymbolicLink() method defined in the Java NIO.2 API.

24. C. Since System.out is a PrintStream that inherits OutputStream and implementsCloseable, line y1 compiles without issue. On the other hand, the Files.copy() doesnot compile because there is no overloaded version of Files.copy() that takes anOutputStream as the first parameter. For this reason, Option C is the correct answer. Ifthe order of the arguments in the Files.copy() call was switched, then the code wouldcompile and print the contents of the file at runtime, making Option D the correctanswer.

25. B. To begin with, the BasicFileAttributeView class contains methods to read andwrite file data, while the BasicFileAttributes class only contains methods to read filedata. The advantage of using a BasicFileAttributeView is to also modify file data, soOption D is incorrect. Next, The BasicFileAttributeView does not include a method tomodify the hidden attribute. Instead, a DosFileAttributeView is required, makingOption A incorrect. Option B is the correct answer because BasicFileAttributeViewincludes a setTimes() method to modify the file date values. Finally, Option C is

incorrect because both read file information in a single round-trip.

26. A. Trick question! The code does not compile, therefore no Path values are printed,and Option A is the correct answer. The key here is that toRealPath() interacts withthe file system and therefore throws a checked IOException. Since this checkedexception is not handled inside the lambda expression, the class does not compile. Ifthe lambda expression was fixed to handle the IOException, then the expected numberof Path values printed would be six, and Option C would be the correct answer. AmaxDepth value of 1 causes the walk() method to visit two total levels, the original/flower and the files it contains.

27. D. The first statement returns a null value, since the path .. does not have a parent.That said, it does not throw an exception at runtime, since it is not operated upon. Thesecond and third statements both return paths representing the root (/) at runtime.Remember that calling getRoot() on a root path returns the root path. The fourthstatement throws a NullPointerException at runtime since getRoot() on a relativepath returns null, with the call to getParent() triggering the exception. Since thefourth statement is the only one to produce a NullPointerException at runtime,Option D is the correct answer.

28. C. The code compiles without issue, so Options A and B are incorrect. While many ofthe Files methods do throw IOException, most of the Path methods do not throw achecked exception. The lack of indent of the return statement on line 6 is intentionaland does not prevent the class from compiling. If the input argument p is null or notan absolute path, then the if-then clause is skipped, and it is returned to the callerunchanged. Alternatively, if the input argument is an absolute path, then callingtoAbsolutePath() has no effect. In both cases, the return value of the method matchesthe input argument, making Option C the correct answer.

29. D. Option A is incorrect because both methods take exactly one Path parameter, alongwith an optional vararg of FileAttribute values. Option B is also incorrect becauseboth methods will throw a FileAlreadyExistsException if the target exists and is afile. Option C is incorrect since both methods declare a checked IOException. Thecorrect answer is Option D. The method createDirectory() creates a single directory,while createDirectories() may create many directories along the path value.

30. C. The toAbsolutePath() combines the current working directory and relative path toform a /hail/../jungle/.././rain.. path. The normalize() method removes the pathsymbols and leaves a /rain.. value. Note that the last double period (..) is notremoved because it is part of a path name and not interpreted as a path symbol. Theresult is then appended with snow.txt and we are left with /rain../snow.txt, makingOption C the correct answer.

31. A. The program compiles and runs without issue, so Options C and D are incorrect.The process breaks apart the inputted path value and then attempts to reconstitute it.There is only one problem. The method call getName(0) does not include the rootelement. This results in the repaired variable having a value of

tissue/heart/chambers.txt, which is not equivalent to the original path. The programprints false, and Option A is the correct answer.

32. B. Unlike Files.delete(), the Files.deleteIfExists() method does not throw anexception if the path does not exist, making Option B the correct answer. Options A, C,and D describe situations in which the Java process encounters a path in a state thatcannot be deleted. In each of these situations, an exception would be thrown atruntime.

33. D. The code does not compile because Path is an interface and does not contain aget() method. Since the first line contains a compilation error, Option D is the correctanswer. If the code was corrected to use Paths.get(), then the output would be truefalse true, and Option B would be the correct answer. The normalized path of both is/desert/sand.doc, which means they would be equivalent, in terms of equals(), andpoint to the same path in the file system. On the other hand, the non-normalizedvalues are not equivalent, in terms of equals(), since the objects represent distinctpath values.

34. C. First off, the Files.getFileAttributeView() method requires a reference to asubclass of FileAttributeView, such as BasicFileAttributeView.class. Theparameter must also be compatible with the reference assignment to vw. For these tworeasons, this line of code does not compile. Next, BasicFileAttributeView does notcontain a creationTime() method, so vw.creationTime() results in a compilationerror. For the exam, remember that view classes do contain access to attributes, butonly through the readAttributes method, such asvw.readAttributes().creationTime(). Since these are the only two lines that containcompilation errors, Option C is the correct answer. Note that we purposely omitted allimport statements in this question, since this may happen on the real exam.

35. B. The program compiles and runs without issue, making Options C and D incorrect.The first variable, halleysComet, is created with normalize() being applied right away,leading to a value of stars/m1.meteor. The second variable, lexellsComet, starts with avalue of ./stars/../solar/. The subpath() call reduces it to its first two components,./stars. The resolve() method then appends m1.meteor, resulting in a value of./stars/m1.meteor. Finally, normalize() further reduces the value tostars/m1.meteor. Since this matches our first Path, the program prints Same!, andOption B is the correct answer.

36. D. Both stream statements compile without issue, making Options A and B incorrect.The two statements are equivalent to one another and print the same values atruntime. For this reason, Option C is incorrect, and Option D is correct. There aresome subtle differences in the implementation besides one using walk() with afilter() and the other using find(). The walk() call does not include a depth limit,but since Integer.MAX_VALUE is the default value, the two calls are equivalent.Furthermore, the walk() statement prints a stream of absolute paths stored as Stringvalues, while the find() statement prints a stream of Path values. If the input p was a

relative path, then these two calls would have very different results, but since we aretold p is an absolute path, the application of toAbsolutePath() does not change theresults.

37. A. The code does not compile because Files.lines() and Files.readAllLines() throwa checked IOException, which must be handled or declared. For the exam, rememberthat other than a handful of test methods, like Files.exists(), most methods in theNIO.2 Files class that operate on file system records declare an IOException. Now, ifthe exceptions were properly handled or declared within the class, then jonReads()would likely take more time to run. Like all streams, Files.lines() loads the contentsof the file in a lazy manner, meaning the time it takes for jenniferReads() to run isconstant regardless of the file size. Note the stream isn’t actually traversed since thereis no terminal operation. Alternatively, Files.readAllLines() reads the entirecontents of the file before returning a list of String values. The larger the file, thelonger it takes jonReads() to execute. Since the original question says the file issignificantly large, then if the compilation problems were corrected, jonReads() wouldlikely take longer to run, and Option C would be the correct answer.

38. C. The first copy() method call on line q1 compiles without issue because it matchesthe signature of a copy() method in Files. It also does not throw an exception becausethe REPLACE_EXISTING option is used and we are told the file is fully accessible withinthe file system. On the other hand, the second copy() method on line q2 does notcompile. There is a version of Files.copy() that takes an InputStream, followed by aPath and a list of copy options. Because BufferedReader does not inherit InputStream,though, there is no matching copy() method and the code does not compile. For thisreason, Option C is the correct answer.

39. C. The Files.isSameFile() throws a checked IOException. Even though accessing thefile system can be skipped in some cases, such as if the Path instances are equivalentin terms of equals(), the method still declares IOException since it may access the filesystem to determine if the two Path instances refer to the same file. For this reason,Option C is the correct answer. The rest of the methods listed do not throw anychecked exceptions, even though they do access the file system, instead returningfalse if the file does not exist.

40. B. The program compiles and runs without issue, making Options C and D incorrect.The program uses Files.list() to iterate over all files within a single directory. Foreach file, it then iterates over the lines of the file and counts the sum. For this reason,Option B is the correct answer. If the count() method had used Files.walk() insteadof Files.lines(), then the class would still compile and run, and Option A would bethe correct answer. Note that we had to wrap Files.lines() in a try-catch blockbecause using this method directly within a lambda expression without a try-catchblock leads to a compilation error.

Chapter 20: Java Concurrency1. A. The ExecutorService interface defines the two submit() methods shown in Options

C and D. Because ExecutorService extends Executor, it inherits theexecute(Runnable) method presented in Option B. That leaves us with the correctanswer, Option A, because ExecutorService does not define nor inherit an overloadedmethod execute() that takes a Callable parameter.

2. B. The class compiles and runs without throwing an exception, making the firststatement true. The class defines two values that are incremented by multiple threadsin parallel. The first IntStream statement uses an atomic class to update a variable.Since updating an atomic numeric instance is thread-safe by design, the first numberprinted is always 10, and the second statement is true. The second IntStreamstatement uses an int with the pre-increment operator (++), which is not thread-safe.It is possible two threads could update and set the same value at the same time, aform of race condition, resulting in a value less than 5. For this reason, the thirdstatement is not true. Since only the first two statements are true, Option B is thecorrect answer.

3. C. Option A is incorrect, although it would be correct if Executors was replaced withExecutorService in the sentence. While an instance of ExecutorService can beobtained from the Executors class, there is no method in the Executors class thatperforms a task directly. Option B is also incorrect, but it would be correct if start()was replaced with run() in the sentence. It is recommended that you override therun() method, not the start() method, to execute a task using a custom Thread class.Option C is correct, and one of the most common ways to define an asynchronoustask. Finally, Option D is incorrect because Options A and B are incorrect.

4. D. Trick question! ExecutorService does not contain any of these methods. In order toobtain an instance of a thread executor, you need to use the Executors factory class.For this reason, Option D is the correct answer. If the question had instead askedwhich Executors method to use, then the correct answer would be Option C. Options Aand B do not allow concurrent processes and should not be used with a CyclicBarrierexpecting to reach a limit of five concurrent threads. Option C, on the other hand, willcreate threads as needed and is appropriate for use with a CyclicBarrier.

5. C. CopyOnWriteArrayList makes a copy of the array every time it is modified,preserving the original list of values the iterator is using, even as the array is modified.For this reason, the for loop using copy1 does not throw an exception at runtime. Onthe other hand, the for loops using copy2 and copy3 both throwConcurrentModificationException at runtime since neither allows modification whilethey are being iterated upon. Finally, the ConcurrentLinkedQueue used in copy4completes without throwing an exception at runtime. For the exam, remember thatthe Concurrent classes order read/write access such that access to the class isconsistent across all threads and processes, while the synchronized classes do not.

Because exactly two of the for statements produce exceptions at runtime, Option C isthe correct answer.

6. C. Resource starvation is when a single active thread is perpetually unable to gainaccess to a shared resource. Livelock is a special case of resource starvation, in whichtwo or more active threads are unable to gain access to shared resources, repeating theprocess over and over again. For these reasons, Option C is the correct answer.Deadlock and livelock are similar, although in a deadlock situation the threads arestuck waiting, rather than being active or performing any work. Finally, a racecondition is an undesirable result when two tasks that should be completedsequentially are completed at the same time.

7. B. The class does not compile because the Future.get() on line 8 throws a checkedInterruptedException and ExecutionException, neither of which is handled nordeclared by the submitReports() method. If the submitReports() and accompanyingmain() methods were both updated to declare these exceptions, then the applicationwould print null at runtime, and Option A would be the correct answer. For the exam,remember that Future can be used with Runnable lambda expressions that do not havea return value but that the return value is always null when completed.

8. A. Options B and C are both proper ways to obtain instances of ExecutorService.Remember that newSingleThreadExecutor() is equivalent to callingnewFixedThreadPool() with a value of 1. Option D is the correct way to request asingle-threaded ScheduledExecutorService instance. The correct answer is Option A.The method newFixedScheduledThreadPool() does not exist in the Executors class,although there is one called newScheduledThreadPool().

9. A. The code compiles without issue but hangs indefinitely at runtime. The applicationdefines a thread executor with a single thread and 12 submitted tasks. Because onlyone thread is available to work at a time, the first thread will wait endlessly on the callto await(). Since the CyclicBarrier requires four threads to release it, the applicationwaits endlessly in a frozen condition. Since the barrier is never reached and the codehangs, the application will never output Ready, making Option A the correct answer. IfnewCachedThreadPool() had been used instead of newSingleThreadExecutor(), thenthe barrier would be reached three times, and Option C would be the correct answer.

10. D. First off, BlockingDeque is incorrect since it is an interface, not a class. Next,ConcurrentLinkedDeque does support adding elements to both ends of an ordered datastructure but does not include methods for waiting a specified amount of time to doso, referred to as blocking. ConcurentSkipListSet is also incorrect, since its elementsare sorted and not just ordered, and it does not contain any blocking methods. Thatleaves the correct answer, Option D. A LinkedBlockingDeque includes blockingmethods in which elements can be added to the beginning or end of the queue, whilewaiting at most a specified amount of time.

11. A. The findAny() method can return any element of the stream, regardless of whetherthe stream is serial or parallel. While on serial streams this is likely to be the first

element in the stream, on parallel streams the result is less certain. For this reason,Option A is the correct answer. When applied to an ordered stream, the rest of themethods always produce the same results on both serial and parallel streams. For thisreason, these operations can be costly on a parallel stream since it has to be forcedinto a serial process.

12. D. The static method Array.asList() returns a List instance, which inherits theCollection interface. While the Collection interface defines a stream() andparallelStream() method, it does not contain a parallel() method. For this reason,the second stream statement does not compile, and Option D is the correct answer. Ifthe code was corrected to use parallelStream(), then the arrays would be consistentlyprinted in the same order, and Option C would be the correct answer. Remember thatthe forEachOrdered() method forces parallel streams to run in sequential order.

13. D. To start with, the ForkJoinTask is the parent class of RecursiveAction andRecursiveTask and does not contain a compute() method, neither abstract norconcrete, making Options A and C automatically incorrect. The RecursiveTask classcontains the abstract compute() method that utilizes a generic return type, while theRecursiveAction class contains the abstract compute() method that uses a void returntype. For this reason, Option D is the correct answer.

14. B. An accumulator in a serial or parallel reduction must be associative and stateless. Ina parallel reduction, invalid accumulators tend to produce more visible errors, wherethe result may be processed in an unexpected order. Option A is not associative, since(a-b)-c is not the same as a-(b-c) for all values a, b, and c. For example, using valuesof 1, 2, and 3 results in two different values, -4 and 2. Option C is not stateless, since aclass or instance variable i is modified each time the accumulator runs. That leaves uswith Option B, which is the correct answer since it is both stateless and associative.Even though it ignores the input parameters, it meets the qualifications forperforming a reduction.

15. B. The code does not compile because Callable must define a call() method, not arun() method, so Option B is the correct answer. If the code was fixed to use thecorrect method name, then it would complete without issue, printing Done! atruntime, and Option A would be the correct answer.

16. C. Part of synchronizing access to a variable is ensuring that read/write operations areatomic, or happen without interruption. For example, an increment operation requiresreading a value and then immediately writing it. If any thread interrupts this process,then data could be lost. In this regard, Option C shows proper synchronized access.Thread 2 reads a value and then writes it without interruption. Thread 1 then reads thenew value and writes it. The rest of the answers are incorrect because one threadwrites data to the variable in-between another thread reading and writing to the samevariable. Because a thread is writing data to a variable that has already been written toby another thread, it may set invalid data. For example, two increment operationsrunning at the same time could result in one of the increment operations being lost.

17. D. The code compiles and runs without issue. The two methods hare() and tortoise()are nearly identical, with one calling invokeAll() and the other calling invokeAny().The key is to know that both methods operate synchronously, waiting for a result fromone or more tasks. Calling the invokeAll() method causes the current thread to waituntil all tasks are finished. Since each task is one second long and they are beingexecuted in parallel, the hare() method will take about one second to complete. TheinvokeAny() method will cause the current thread to wait until at least one task iscomplete. Although the result of the first finished thread is often returned, it is notguaranteed. Since each task takes one second to complete, though, the shortestamount of time this method will return is after one second. In this regard, thetortoise() method will also take about one second to complete. Since both methodstake about the same amount of time, either may finish first, causing the output to varyat runtime and making Option D the correct answer. Note that after this programprints the two strings, it does not terminate, since the ExecutorService is not shutdown.

18. B. ConcurrentSkipListMap implements the SortedMap interface, in which the keys arekept sorted, making Option B the correct answer. While the other answers defineordered data structures, none are guaranteed to be sorted. Remember, if you seeSkipList as part of a concurrent class name, it means it is sorted in some way, such asa sorted set or map.

19. D. The synchronized block used in the getQuestion() method requires an object tosynchronize on. Without it, the code does not compile, and Option D is the correctanswer. What if the command was fixed to synchronize on the current object, such asusing synchronized(this)? Each task would obtain a lock for its respective object,then wait a couple of seconds before requesting the lock for the other object. Since thelocks are already held, both wait indefinitely, resulting in a deadlock. In this scenario,Option A would be the correct answer since a deadlock is the most likely result. Wesay most likely because even with corrected code, a deadlock is not guaranteed. It ispossible, albeit very unlikely, for the JVM to wait five seconds before starting thesecond task, allowing enough time for the first task to finish and avoiding thedeadlock completely.

20. B. The ScheduledExecutorService does not include a scheduleAtFixedDelay() method,so Option A is incorrect. The scheduleAtFixedRate() method creates a new task forthe associated action at a set time interval, even if previous tasks for the same actionare still active. In this manner, it is possible multiple threads working on the sameaction could be executing at the same time, making Option B the correct answer. Onthe other hand, scheduleWithFixedDelay() waits until each task is completed beforescheduling the next task, guaranteeing at most one thread working on the action isactive in the thread pool.

21. D. The application compiles, so Option B is incorrect. The stroke variable is thread-safe in the sense that no write is lost since all writes are wrapped in a synchronized

method, making Option C incorrect. Even though the method is thread-safe, the valueof stroke is read while the threads may still be executing. The result is it may output 0,1000, or anything in-between, making Option D the correct answer. If theExecutorService method awaitTermination() is called before the value of stroke isprinted and enough time elapses, then the result would be 1000, and Option A wouldbe the correct answer.

22. B. A race condition is an undesirable result when two tasks that should be completedsequentially are completed at the same time. The result is often corruption of data insome way. If two threads are both modifying the same int variable and there is nosynchronization, then a race condition can occur with one of the writes being lost. Forthis reason, Option B is the correct answer. Option A is the description of resourcestarvation. Options C and D are describing livelock and deadlock, respectively.

23. A. The code compiles, so Option C is incorrect. The application attempts to count theelements of the sheep array, recursively. For example, the first two elements aretotaled by one thread and added to the sum of the remainder of the elements in thearray, which is calculated by another thread. Unfortunately, the class contains a bug.The count value is not marked static and not shared by all of the CountSheepsubtasks. The value of count printed in the main() menu comes from the firstCountSheep instance, which does not modify the count variable. The application prints0, and Option A is the correct answer. If count was marked static, then theapplication would sum the elements correctly, printing 10, and Option B would be thecorrect answer.

24. D. First off, certain stream operations, such as limit() or skip(), force a parallelstream to behave it a serial manner, so Option A is incorrect. Option B is alsoincorrect. Although some operations could take less time to execute, there is noguarantee any operation will actually be faster. For example, the JVM may onlyallocate a single thread to a parallel stream. In other words, parallel streams mayimprove performance but do not guarantee it. Option C is incorrect because parallelstream operations are not synchronized. It is up to the developer to providesynchronization or use a concurrent collection if required. Finally, Option D is thecorrect answer. The BaseStream interface, which all streams inherit, includes aparallel() method. Of course, the results of an operation may change in the presenceof a parallel stream, such as when a stateful lambda expression is used, but they allcan be made parallel.

25. A. The code compiles and runs without issue. The JVM will fall back to a single-threaded process if all of the conditions for performing the parallel reduction are notmet. The stream used in the main() method is not parallel, but thegroupingbyConcurrent() method can still be applied without throwing an exception atruntime. Although performance will suffer from not using a parallel stream, theapplication will still process the results correctly. Since the process groups the data byyear, Option A is the correct answer.

26. A. The code compiles and runs without issue. The three-argument reduce() methodreturns a generic type, while the one-argument reduce() method returns an Optional.The concat1() method is passed an identity "a", which it applies to each element,resulting in the reduction to aCataHat. The lambda expression in the concat2()method reverses the order of its inputs, leading to a value of HatCat. Therefore, OptionA is the correct answer.

27. A. The code compiles without issue, so Options B and C are incorrect. The f1declaration uses the version of submit() in ExecutorService, which takes a Runnableand returns a Future<?>. The call f1.get() waits until the task is finished and alwaysreturns null, since Runnable expressions have a void return type. The f2 declarationuses an overloaded version of submit(), which takes a Callable expression andreturns a generic Future object. Since the double value can be autoboxed to a Doubleobject, the line compiles without issue with f2.get() returning 3.14159. For thesereasons, Option A is the correct answer. Option D is incorrect because no exception isexpected to be thrown at runtime.

28. C. The class compiles without issue, making Options A and D incorrect. The classattempts to create a synchronized version of a List<Integer>. The size() andaddValue() help synchronize the read/write operations. Unfortunately, the getValue()method is not synchronized so the class is not thread-safe, and Option C is the correctanswer. It is possible that one thread could add to the data object while another threadis reading from the object, leading to an unexpected result. Note that thesynchronization of the size() method is valid, but since ThreadSafeList.class is ashared object, this will synchronize all instances of the class to the same object. Thiscould result in a substantial performance cost if enough threads are creatingThreadSafeList objects.

29. D. The post-decrement operator (––) decrements a value but returns the originalvalue. It is equivalent to the atomic getAndDecrement() method. The pre-incrementoperator (++) increments a value and then returns the new value. It is equivalent tothe incrementAndGet() atomic operation. For these reasons, Option D is the correctanswer.

30. B. When a CyclicBarrier goes over its limit, the barrier count is reset to zero. Theapplication defines a CyclicBarrier with a barrier limit of 5 threads. The applicationthen submits 12 tasks to a cached executor service. In this scenario, a cached threadexecutor will use between 5 and 12 threads, reusing existing threads as they becomeavailable. In this manner, there is no worry about running out of available threads.The barrier will then trigger twice, printing five 1s for each of the sets of threads, for atotal of ten 1s. For this reason, Option B is the correct answer. The application thenhangs indefinitely, as discussed in the next question.

31. D. The application does not terminate successfully nor produce an exception atruntime, making Options A and B incorrect. It hangs at runtime because theCyclicBarrier limit is five, while the number of tasks submitted and awaiting

activation is 12. This means that 2 of the tasks will be left over, stuck in a deadlockedstate waiting for the barrier limit to be reached but with no more tasks available totrigger it. For this reason, Option D is the correct answer. If the number of tasks was amultiple of the barrier limit, such as 10 instead of 12, then the application will stillhang because the ExecutorService is never shut down. The isShutdown() in theapplication finally block does not trigger a shutdown. Remember that it is importantto shut down an ExecutorService after you are finished with it, else it can prevent aprogram from terminating. In this case, Option C would be the correct answer.

32. C. The code does not compile because the blocking methods offerLast() andpollFirst() each throw a checked InterruptedException that are not handled by thelambda expressions, so Option C is the correct answer. If the lambda expressions werewrapped with try-catch blocks, then the process would first add all items to the queue,then remove them all of them, resulting in an output of 0. In this case, Option A wouldbe the correct answer. Even though the tasks are completed in parallel, each streamdoes not terminate until all tasks are done. Note that 10 seconds is more than enoughtime under normal circumstances to add/remove elements from the queue.

33. A. First of all, the for loops using copy1 and copy4 both throwConcurrentModificationException at runtime since neither allows modification whilethey are being iterated upon. Next, CopyOnWriteArrayList makes a copy of the arrayevery time it is modified, preserving the original list of values the iterator is using,even as the array is modified. For this reason, the for loop using copy2 completeswithout throwing an exception or creating an infinite loop. Finally, theConcurrentLinkedDeque used in copy3 completes without producing an exception orinfinite loop. The Concurrent collections order read/write access such that access tothe class is consistent across all threads and processes, even iterators. Because thevalues are inserted at the head of the queue using push() and the underlying datastructure is ordered, the new values will not be iterated upon and the loop finishes.Since none of the for statements produce an infinite loop at runtime, Option A is thecorrect answer. If push() had been used instead of offer() in the third loop, with newvalues being inserted at the tail of the queue instead of at the head, then the for loopwould have entered an infinite loop, and Option B would be the correct answer.

34. B. Options A, C, and D are the precise requirements for Java to perform a concurrentreduction using the collect() method, which takes a Collector argument. Recallfrom your studies that a Collector is considered concurrent and unordered if it hasthe Collector.Characteristics enum values CONCURRENT and UNORDERED, respectively.Option B is the correct answer because elements of a stream are not required toimplement Comparable in order to perform a parallel reduction.

35. D. The class compiles and runs without issue, making Options A and B incorrect. Thepurpose of the fork/join framework is to use parallel processing to complete subtasksacross multiple threads concurrently. Unfortunately, calling the compute() methodinside of an existing compute() does not spawn a new thread. The result is that this

task is completed using a single thread, despite a pool of threads being available. Forthis reason, Option D is the correct answer. In order to properly implement thefork/join framework, the compute() method would need to be rewritten. Thef1.compute() call should be replaced with f1.fork() to spawn a separate task,followed by f2.compute() to process the data on the current thread, and ending inf1.join() to retrieve the results of the first task completed while f2.compute() wasbeing processed. If the code was rewritten as described, then Option C would be thecorrect answer.

36. D. The shutdown() method prevents new tasks from being added but allows existingtasks to finish. In addition to preventing new tasks from being added, theshutdownNow() method also attempts to stop all running tasks. Neither of thesemethods guarantee any task will be stopped, making Option D the correct answer.Option C is incorrect because there is no halt() method in ExecutorService.

37. B. First off, the class uses a synchronized list, which is thread-safe and allowsmodification from multiple threads, making Option D incorrect. The process generatesa list of numbers from 1 to 5 and sends them into a parallel stream where the map() isapplied, possibly out of order. This results in elements being written to db in a randomorder. The stream then applies the forEachOrdered() method to its elements, whichwill force the parallel stream into a single-threaded state. At runtime, line p1 will printthe results in order every time as 12345. On the other hand, since the elements wereadded to db in a random order, the output of line p2 is random and cannot be predictedahead of time. Since the results may sometimes be the same, Option B is the correctanswer. Part of the reason that the results are indeterminate is that the question usesa stateful lambda expression, which based on your studies should be avoided inpractice!

38. C. The program compiles and does not throw an exception at runtime, making OptionsB and D incorrect. The class attempts to add and remove values from a single cookievariable in a thread-safe manner but fails to do so because the methods deposit() andwithdrawal() synchronize on different objects. The instance method deposit()synchronizes on the bank object, while the static method withdrawal() synchronizeson the static Bank.class object. Even though method calls of the same type areprotected, calls across the two different methods are not. Since the compoundassignment operators (+=) and (-=) are not thread-safe, it is possible for one call tomodify the value of cookies while the other is already operating on it, resulting in aloss of information. For this reason, the output cannot be predicted, and Option C isthe correct answer. If the two sets of calls were properly synchronized on the sameobject, then the cookies variable would be protected from concurrent modifications,and Option A would be the correct answer.

39. A. The code attempts to search for a matching element in an array recursively. While itdoes not contain any compilation problems, it does contain an error. Despite creatingThread instances, it is not a multi-threaded program. Calling run() on a Thread runs

the process as part of the current thread. To be a multi-threaded execution, it wouldneed to instead call the start() method. For this reason, the code completessynchronously, waiting for each method call to return before moving on to the nextand printing true at the end of the execution, making Option A the correct answer. Onthe other hand, if start() had been used, then the application would be multi-threaded but then the result may not be ready by the time the println() method iscalled, resulting in a value that cannot be predicted ahead of time. In this case, OptionD would be the correct answer.

40. C. Line 13 does not compile because the execute() method has a return type of void,not Future. Line 15 does not compile because scheduleAtFixedRate() requires fourarguments that include an initial delay and period value. For these two reasons,Option C is the correct answer.

Chapter 21: Building Database Applications with JDBC1. C. Connection is an interface for communicating with the database. Driver is tricky

because you don’t write code that references it directly. However, you are still requiredto know it is a JDBC interface. DriverManager is used in JDBC code to get aConnection. However, it is a concrete class rather than an interface. Since Connectionand Driver are JDBC interfaces, Option C is correct.

2. D. Database-specific implementation classes are not in the java.sql package. Theimplementation classes are in database drivers and have package names that arespecific to the database. Therefore, Option D is correct. The Driver interface is in thejava.sql package. Note that these classes may or may not exist. You are not requiredto know the names of any database-specific classes, so the creators of the exam iarefree to make up names.

3. D. All JDBC URLs begin with the protocol jdbc followed by a colon as a delimiter.Option D is the only one that does both of these, making it the answer.

4. A. The Driver interface is responsible for getting a connection to the database, makingOption A the answer. The Connection interface is responsible for communication withthe database but not making the initial connection. The Statement interface knowshow to run the SQL query, and the ResultSet interface knows what was returned by aSELECT query.

5. B. The requirement to include a java.sql.Driver file in the driver jar file wasintroduced in JDBC 4.0. A 3.0 driver is allowed, but not required, to include this file.JDBC 3.0 also requires a call to Class.forName(). As a result, Option B best fills in theblanks.

6. C. Connection is an interface. Since interfaces do not have constructors, Option D isincorrect. The Connection class doesn’t have a static method to get a Connectioneither, making Option A incorrect. The Driver class is also an interface without staticmethods, making Option B incorrect. Option C is the answer because DriverManager isthe class used in JDBC to get a Connection.

7. B. The DriverManager.getConnection() method can be called with just a URL. It isalso overloaded to take the URL, username, and password, making Option B correct.

8. D. CallableStatement and PreparedStatement are interfaces that extend the Statementinterface. You don’t need to know that for the exam. You do need to know that adatabase driver is required to provide the concrete implementation class of Statementrather than the JDK. This makes Option D correct. Note that while Derby is providedwith Java, it is in a separate jar from the “main” JDK.

9. C. A JDBC URL has three components separated by colons. All three of these URLsmeet those criteria. For the data after the component, the database driver specifies theformat. Depending on the driver, this might include an IP address and port.Regardless, it needs to include the database name or alias. I and II could both be valid

formats because they mention the database box. However, III only has an IP addressand port. It does not have a database name or alias. Therefore III is incorrect andOption C correct.

10. C. The requirement to include a java.sql.Driver file in the driver jar was introducedin JDBC 4.0. A call to Class.forName() was made optional with JDBC 4.0. As a result,Option C best fills in the blanks.

11. A. Scroll sensitive is a result set type parameter, and updatable is a concurrency mode.The result set type parameter is passed to createStatement() before the concurrencymode. If you request options that the database driver does not support, it downgradesto an option it does support rather than throwing an exception. Statements I and IIIare correct, making Option A the answer.

12. B. JDBC 4.0 allows, but does not require, a call to the Class.forName() method.However, since it is in the code, it needs to be correct. This method is expecting a fullyqualified class name of a database driver, not the JDBC URL. As a result, theClass.forName() method throws a ClassNotFoundException, and Option B is theanswer.

13. B. There are two ResultSet concurrency modes: CONCUR_READ_ONLY andCONCUR_UPDATABLE. All database drivers support read-only result sets, but not allsupport updatable ones. Therefore, Option B is correct.

14. D. This code is missing a call to rs.next(). As a result, rs.getInt(1) throws aSQLException with the message Invalid cursor state – no current row. Therefore,Option D is the answer.

15. D. The execute() method is allowed to run any type of SQL statements. TheexecuteUpdate() method is allowed to run any type of the SQL statement that returnsa row count rather than a ResultSet. Both DELETE AND UPDATE SQL statements areallowed to be run with either execute() or executeUpdate(). They are not allowed tobe run with executeQuery() because they do not return a ResultSet. Therefore, OptionD is the answer.

16. C. Connection is an interface rather than a concrete class. Therefore, it does not have aconstructor and line s2 does not compile. As a result, Option C is the answer. Option Awould be the answer if the code new Connection() was changed toDriverManager.getConnection().

17. A. There are three ResultSet type options: TYPE_FORWARD_ONLY,TYPE_SCROLL_INSENSITIVE, and TYPE_SCROLL_SENSITIVE. Only one of these is in the list,making Option A correct.

18. B. Unlike arrays, JDBC uses one-based indexes. Since num_pages is in the secondcolumn, the parameter needs to be 2, ruling out Options A and C. Further, there is nota method named getInteger() on the ResultSet interface, ruling out Option D. Sincethe proper method is getInt(), Option B is the answer.

19. D. Option A does not compile because you have to pass a column index or columnname to the method. Options B and C compile. However, there are not columnsnamed 0 or 1. Since these column names don’t exist, the code would throw aSQLException at runtime. Option D is correct as it uses the proper column name.

20. B. The parameters to createStatement() are backward. However, they still compilebecause both are of type int. This means the code to create the Statement doescompile, and Option A is incorrect. Next comes the code to create the ResultSet. Whileboth execute() and executeQuery() can run a SELECT SQL statement, they havedifferent return types. Only executeQuery() can be used in this example. The codedoes not compile because the execute() method returns a boolean, and Option B iscorrect. If this was fixed, Option D would be the answer because rs.next() is nevercalled.

21. D. Since this code opens Statement using a try-with-resources, Statement gets closedautomatically at the end of the block. Further, closing a Statement automaticallycloses a ResultSet created by it, making Option D the answer. Remember that youshould close any resources you open in code you write.

22. C. Option A is incorrect because Driver is an interface while DriverManager is aconcrete class. The inverse isn’t true either; DriverManager doesn’t implement Driver.Option B is incorrect because the Connection implementation comes from thedatabase driver jar. Option C is correct. You can turn off auto-commit mode, but itdefaults to on. Option D is incorrect because you need to call rs.next() or anequivalent method to point to the first row.

23. C. The requirement to include a java.sql.Driver file in the META-INF directory wasintroduced in JDBC 4.0. Older drivers are not required to provide it, making Option Bincorrect. A file named jdbc.driver has never been a requirement. Option A isincorrect and is simply here to trick you. All drivers are required to implement theConnection interface, making Option C the answer.

24. D. First, rs.next() moves the cursor to point to the first row, which contains thenumber 10. Line q1 moves the cursor to immediately before the first row. This is thesame as the position it was in before callingrs.next() in the first place. It is a validposition but isn’t a row of data. Line q2 tries to retrieve the data at this position andthrows a SQLException because there isn’t any data, making Option D the answer.

25. B. This code shows how to properly update a ResultSet. Note that it calls updateRow()so the changes get applied in the database. This allows the SELECT query to see thechanges and output 10. Option B is correct. Remember that unlike this code, youshould always close a ResultSet when you open it in real code.

26. C. There is no ResultSet method named prev(). Therefore, the code doesn’t compile,and Option C is correct. If prev() was changed to previous(), the answer would beOption B because updateRow() is never called. Remember that unlike this code, youshould always close a ResultSet when you open it in real code.

27. D. While the code turns off automatic committing, there is a commit() statement afterthe first two inserts that explicitly commits those to the database. Then automaticcommit is turned back on and the third commit is made, making Option D the answer.

28. A. The count(*) function in SQL always returns a number. In this case, it is thenumber zero. This means line r1 executes successfully because it positions the cursorat that row. Line r2 also executes successfully and prints 0, which is the value in therow. Since the code runs successfully, Option A is the answer.

29. B. The cursor starts out at position zero, right before the first row. Line 6 moves thecursor to position five. Line 7 tries to move the cursor ten rows before that positionwhich is row negative five. Since you can’t move back before row zero, the cursor is atrow zero instead. Then line 8 moves the cursor forward five positions from row zero,leaving it at row five and making Option B the answer.

30. C. JDBC 4.0 allows, but does not require, a call to the Class.forName() method. Sincethe database does not exist, DriverManager.getConnection() throws a SQLException,and Option C is the answer.

31. D. When running a query on a Statement, Java closes any already open ResultSetobjects. This means that rs1 is closed on line 8. Therefore, it throws a SQLException online 9 because we are trying to call next() on a closed ResultSet, and Option D iscorrect.

32. B. The code turns off automatic committing, so the inserts for red and blue are notimmediately made. The rollback() statement actually prevents them from beingcommitted. Then automatic commit is turned back on and one insert is made, makingOption B the answer.

33. A. This code correctly obtains a Connection and Statement. It then runs a query,getting back a ResultSet without any rows. The rs.next() call returns false, sonothing is printed, making Option A correct.

34. B. Since the ResultSet type allows scrolling, the code does not throw a SQLException atruntime. Immediately after getting the ResultSet, the cursor is positioned at the endimmediately after Scott’s row. The next two lines try to move forward one row. Thishas no effect since the cursor is already at the end. Then previous() moves the cursorto point to the last row, which is Scott’s row. The second previous() call moves thecursor up one more row to point to Elena’s row, making Option B the answer.

35. B. When passing a negative number to absolute(), Java counts from the end insteadof the beginning. The last row is Scott’s row, so the first print statement outputs Scott.When passing a positive number to absolute(), Java counts from the beginning, soJeanne is output. Therefore, Option B is correct.

36. D. When creating the Statement, the code doesn’t specify a result set type. This meansit defaults to TYPE_FORWARD_ONLY. The absolute() method can only be called onscrollable result sets. The code throws a SQLException, making Option D the answer.

37. B. This code does not compile because the ResultSet options need to be suppliedwhen creating the Statement object rather than when executing the query. Since thecode does not compile, Option B is correct.

38. B. The code turns off automatic committing, so the inserts for red and blue are notimmediately made. The rollback() statement says to prevent any changes made fromoccurring. This gets rid of red and blue. Then automatic commit is turned back on andthe one insert for green is made. The final rollback has no effect since the commit wasautomatically made. Since there was one row added, Option B is the answer.

39. D. Line 18 doesn’t compile because beforeFirst() has a void return type. Since thecode doesn’t compile, it doesn’t print true at all, and Option D is correct. If line 18called rs.beforeFirst() without trying to print the result, Option B would be theanswer. All the other statements are valid and return true.

40. B. When manually closing database resources, they should be closed in the reverseorder from which they were opened. This means that the ResultSet object is closedbefore the Statement object and the Statement object is closed before the Connectionobject. This makes Option B the answer.

Chapter 22: Localization1. D. Oracle defines a locale as a geographical, political, or cultural region. Time zones

often span multiple locales, so Option D is correct.

2. C. Currencies vary in presentation by locale. For example, 9,000 and 9.000 bothrepresent nine thousand, depending on the locale. Similarly, for dates, 01-02-1991 and02-01-1991 represent January 2, 1991, depending on the locale. This makes Option Cthe answer.

3. C. The Locale object provides getDefault() and setDefault() methods for workingwith the default locale, so Option C is correct. There is no get() method declared onLocale.

4. A. Internationalization means the program is designed so it can be adapted formultiple languages. By extracting the town names, this is exactly what has happenedhere, making Option A correct. Localization means the program actually supportsmultiple locales. There’s no mention of multiple locales here, so Option B is incorrect.Similarly, there is no mention of multiple languages, making Option D incorrect.Finally, specialization is not a term relevant to properties, making Option C incorrect.

5. A. The Properties class is a Map, making III correct. Hashtable and HashMap areconcrete classes rather than interfaces, so I and II are incorrect. While a Propertiesobject is a Hashtable, this is not an interface. Since only III is correct, Option A is theanswer.

6. C. Java supports properties file resource bundles and Java class resource bundles.Properties file resource bundles contain String keys and String values. Java classresource bundles contain String keys and any type of classes as values. Since both arevalid, Option C is correct.

7. B. Calling Locale.setDefault() changes the default locale within the program. It doesnot change any settings on the computer. The next time you run a Java program, itwill have the original default locale rather than the one you changed it to.

8. B. Line 18 prints the value for the property with the key mystery, which is bag. Line 19prints a space. Line 20 doesn’t find the key more so it prints null. Therefore, it printsbag null, and Option B is correct.

9. C. There is not a built-in class called JavaResourceBundle, making Options A and Bincorrect. The ListResourceBundle class is used to programmatically create a resourcebundle. It requires one method to be implemented named getContents(), makingOption D incorrect and Option C correct. This method returns a 2D array of key/valuepairs.

10. A. When both a language and country code are present, the language code comes first.The language code is in all lowercase letters and the country code is in all uppercase.

11. C. Java starts out by looking for a Java file with the most specific match, which is

language and country code. Since this is happening at runtime, it is looking for thecorresponding file with a .class extension. This matches Option C, making it theanswer. If this file was not found, Java would then look for a .properties file with thename, which is Option D. If neither was found, it would continue droppingcomponents of the name, eventually getting to Options A and B in that order.

12. A. This class correctly creates a Java class resource bundle. It extendsListResourceBundle and creates a 2D array as the property contents. Since count is anint, it is autoboxed into an Integer. In the main() method, it gets the resource bundlewithout a locale and requests the count key. Since Integer is a Java Object, it callsgetObject() to get the value. The value is not incremented each time because thegetContents() method is only called once. Therefore, Option A is correct.

13. A. A Locale can consist of a language only, making Option A correct. It cannot consistof a country code without a language, so Option B is incorrect. Finally, if both alanguage and country code are present, the language code is first, making Option Cincorrect.

14. A. Java supports properties file resource bundles and Java class resource bundles.Properties file resource bundles require String values, making Option B incorrect.Java class resource bundles allow any type of classes as values. Since the questionasks about defining values, it is the .java source code rather than the .class bytecodefile, making Option A the answer.

15. C. At least one matching resource bundle must be available at the time of the call togetBundle(). While the requested key determines which of the resource bundles isused, at least one must exist simply to get the ResourceBundle reference, so Option Cis the answer.

16. D. The Properties class implements Map. While the get() method, inherited from thesuperclass, is available, it returns an Object. Since Object cannot be cast to String, itdoes not compile, and Option D is the answer.

17. D. Java supports properties file resource bundles and Java class resource bundles.Both require String as the key format, so Option D is the answer.

18. A. Java starts out by looking for a Java file with the most specific match, which islanguage and country code. Since there is no such matching file, it drops the countrycode and looks for a match by language code. Java looks for bytecode files beforeproperties files. Therefore, Option A is the answer. If it wasn’t present, Option B wouldbe the next choice. Options C and D would never be considered, as a locale doesn’t justhave a country code.

19. D. There is no get() method on Locale. You need to use a constructor or a predefinedLocale constant to obtain a Locale object. Therefore, Option D is the correct answer.Option B is close in that Locale.ITALIAN does reference a Locale object. However, itshould not be passed to the nonexistent get() method.

20. A. This code creates a Map with two elements. Then it copies both key/value pairs to aProperties object. This works because a Properties object is also a Map and thereforehas a put() method that takes Object parameters. Finally, the code gets the Stringproperty values of both keys and prints hammer nail. Therefore, Option A is correct.

21. D. The code attempts to create a Java class resource bundle. However, the Type classdoes not extend ListResourceBundle. It compiles, but throws an exception on line 9because no resource bundle is actually defined. Therefore, Option D is correct.

22. D. This code compiles and runs without exception, making Option D the answer. Line3 uses a predefined Locale constant. Line 5 passes a language and country code forEnglish in Australia. Line 7 incorrectly passes capital letters as a language code.However, Java automatically converts it to lowercase without throwing an exception.The three lines printed by the code are ko, en_US and en.

23. C. Line 18 prints the value for the property with key mystery, which is bag. Line 19prints a space. Line 20 doesn’t find the key more so it uses the second parameter ? asthe default value. The code prints bag ?, so Option C is correct.

24. B. The getBundle() method matches Cars_fr_FR.properties since that is therequested locale. The country key is in that properties file directly, so France is used asthe value. The engine key is not, so Java looks higher up in the hierarchy and finds itin the language-specific Cars_fr.properties file and uses moteur as the value.Therefore, Option B is correct. Note that the default locale isn’t used.

25. D. The getBundle() method matches Cars_fr.properties. Since the requested localeof French Canada is not available, it uses the language-specific locale of French. Theengine key is in that properties file directly, so moteur is retrieved as the value.However, we have a problem getting the horses key. It is not in the hierarchy ofCars_fr.properties. It is in the English properties file, but Java cannot look at thedefault locale if it found a match with the requested locale. As a result, the codethrows a MissingResourceException, making Option D the answer.

26. A. The getBundle() method matches Cars_en.properties. Since the requested localeof English Canada is not available, it uses the language-specific locale of English. Theengine key is in that properties file directly, so engine is retrieved as the value. Thehorses key is also in that properties file, so 241 is used as the value, and Option A isthe answer.

27. B. A ListResourceBundle is a Java class that provides key/value pairs. The values canbe any Java class type and can be created at runtime, making Options A and C falsestatements. When you want to provide a language-specific resource bundle, anunderscore and the language code are added after the class name. Since Option B doesnot have an underscore, it is a false statement. Since all three statements are false,Option D is the answer.

28. D. Since a Locale is passed when requesting the ResourceBundle, that Locale is usedfirst when looking for bundles. Since there isn’t a bundle called

Colors_zh_CN.properties, Java goes on to check for the language. Option D provides amatch on language. If this was not found, Java would go on to the default locale,eventually matching Option B. Since country is not used without language, Options Aand C would not be considered as options.

29. B. This class correctly creates a Java class resource bundle. It extendsListResourceBundle and creates a 2D array as the property contents. In the main()method, it gets the resource bundle without a locale and requests the count key. Sincethis is a Java Object, it calls getObject() to get the value and casts it to the correcttype. Then the getCount() method is called twice, incrementing each time, makingOption B the correct answer. Note that having a mutable object as a property is a badpractice.

30. D. Line 10 is incorrect. It tries to get a bundle named Type. However, this code is in apackage and named keyboard.Type. Therefore, a MissingResourceException is thrown,and Option D is correct.

31. B. Since no locale is specified, the code tries to find a bundle matching the defaultlocale. While none of the resource bundles match English United States, two do matchthe language English. The Java class one is used since it is present. Since the Javaresource bundle for English doesn’t have a key wheels, we go up to the parent resourcebundle. The default Java resource bundle does have the key wheels with the value 4, soOption B is correct.

32. D. Since no locale is specified, the code tries to find a bundle matching the defaultlocale. Two resource bundles match the language English. The Java class one is usedsince it is present. However, it does not contain a key color, nor does its parent. Javadoes not allow looking in a properties file resource bundle once it has matched a Javaclass resource bundle. Therefore, it throws a MissingResourceBundleException, andOption D is the answer.

33. B. Since no locale is specified, the code tries to find a bundle matching the defaultlocale. None of the resource bundles match the language, so the default resourcebundle is used. The default Java resource bundle is used since it is present and has thekey wheels with the value 4. Therefore, Option B is correct.

34. A. Since a locale is passed when requesting the ResourceBundle, that locale is used firstwhen looking for bundles. Since there isn’t a bundle for that locale, Java checks for thelanguage zh. There still isn’t a match, so Java goes on to check for the default locale.Still no match. Next Java checks the language of the default locale and finally finds amatch in Option A. If that match wasn’t found, Java would match on Option B, whichis the default bundle. Option C would never be checked since the base name is Redrather than the requested Color.

35. C. A Properties object implements Map. This makes the get() method available.Properties also defined a getProperty() method. Therefore, both methods can fill inthe blank, and Option C is correct.

36. B. This code compiles and runs without issue. It creates a default Java class resourcebundle. Lines 5 through 7 show it has one key and one ArrayList value. Line 9 gets areference to the resource bundle. Lines 10 through 16 retrieve the ArrayList and addsix values to it. Since this is a reference, line 17 gets the same object and prints the sizeof 6. Therefore, Option B is correct.

37. B. The class on line p1 should be Properties rather than Property. As written it isincorrect and does not compile, making Option B the answer.

38. C. ResourceBundle is an abstract class and uses a factory to obtain the right subclass.Since a call to the constructor new ResourceBundle() does not compile, Option C is theanswer. If this was fixed, Option A would be the answer because getContents() is onlycalled once.

39. A. This code sets the default locale to English and then tries to get a resource bundlefor container in the pod package. It finds the resource bundlepod.container_en.properties as the most specific match. Both keys are found in thisfile, so Option A is the answer.

40. D. Option C is not a valid match for this resource bundle because the base name is Redrather than the requested Colors. Options A and B are not valid matches because theycontain uppercase letters for the language code while Java requires lowercase. Sincenone match, Option D is correct, and the code throws an exception at runtime.

Chapter 23: OCP Practice Exam1. A, E. Line 12 has no effect. The cursor starts out positioned immediately before the

first row and beforeFirst() keeps it there. Line 13 moves the cursor to point to rowfive and prints true. Line 14 prints the value in that row, which is 5. Line 15 tries tosubtract 10 rows from the current position. That would be at row negative five.However, the cursor can’t go back further than the beginning, so it stays at row zero. Italso prints false since there isn’t data at row zero. Note this is the same position thecursor was at on line 12. Now we have a problem. Line 16 tries to print a value on rowzero, but there is no data. It instead throws a SQLException, making Option E correct.Option A is also correct since true was only output once.

2. D. While this code misuses formatting characters, it does compile and runsuccessfully, making Options E and F incorrect. A lowercase m represents the minutes,which are 59 in this case, ruling out Options A and B. The rest of the code prints thedate, hour, and month. This gives the value 59.140103, making Option D the answer.

3. A, B, E. First off, Option A is a valid functional interface that matches the Runnablefunctional interface. Option B is also a valid lambda expression that matchesFunction<Double,Double>, among other functional interfaces. Option C is incorrectbecause the local variable w cannot be declared again in the lambda expression bodysince it is already declared in the lambda expression. Option D is also incorrect. If thedata type is specified for one variable in a lambda expression, it must be specified forall variables within the expression. Next, Option E is correct because this lambdaexpression matches the UnaryOperator functional interface. Lastly, Option F isincorrect. The statement name.toUpperCase() is missing a semicolon (;) that isrequired to terminate the statement.

4. D. The code does not compile, so Options A, B, and F are incorrect. The firstcompilation error is in the declaration of the lambda expression for second. It does notuse a generic type, which means t is of type Object. Since Object, unlike String, doesnot have a method equalsIgnoreCase(), the lambda expression does not compile. Thesecond compilation issue is in the lambda expression in the main() method. Noticethat process() takes an ApplyFilter instance, and ApplyFilter is a functionalinterface that takes a List<String> object. For this reason, q in this lambda expressionis treated as an instance of List<String>. The forEach() method defined inCollections requires a Consumer instance, not a Function, so the callq.forEach(first) does not compile. For these two reasons, Option D is the correctanswer, since the rest of the code compiles without issue.

5. B. First, remember that you are supposed to assume missing imports are present soyou can act as if java.util and java.util.stream are imported. This code doescompile. Line r1 is a valid lambda definition of a Comparator. Line r2 is valid code tosort a stream in a descending order and print the values. Therefore, Option B iscorrect.

6. F. The first catch block on line p1 does not compile because AddingException andDividingException are checked exceptions, and the compiler detects these exceptionsare not capable of being thrown by the associated try block. The second catch blockon line p2 also does not compile, although for a different reason. UnexpectedExceptionis a subclass of RuntimeException, which in turn extends Exception. This makesUnexpectedException a subclass of Exception, causing the compiler to considerUnexpectedException redundant. For these two reasons, the code does not compile,and Option F is the correct answer.

7. A. The code compiles and runs without issue, making Option A the correct answer.Enums are usually named like classes and have enum values that are all uppercase.While a format like Colors.RED or Colors.GREEN is the common convention, alternateformats like COLORS.blue do compile. Next, note the enum properly implements theHasHue interface even though there’s no enum-level method, with each value havingits own implementation. Also, line 10 does not end with a semicolon (;). Becausethere are no methods or constructors defined outside the value list, a semicolon (;) isnot required. The enum class and the rest of the application compile without issue,printing Painting: 00FF00 at runtime.

8. C. Java 8 date and time classes are immutable. They use a static factory method toget the object reference rather than a constructor. This makes II, IV, and VI incorrect.Further, there is not a ZonedDate class. There is a ZonedDateTime class. Thisadditionally makes V incorrect. Both I and III compile, so Option C is correct.

9. C, F. The Optional does not contain a value. While there is a get() method onOptional, it doesn’t take any parameters, making Options A and B incorrect. Option Cis the simplest way to print the desired result. The orElse() method returns theparameter passed if the Optional is empty. The orElseGet() method runs the Supplierpassed as a parameter, making Option F correct as well.

10. B. This class is never instantiated, so the instance initializer never outputs 1 and theconstructor never outputs 3. This rules out Options A, D, and E. A static initializeronly runs once for the class, which rules out Option C. Option B is correct because thestatic initializer runs once printing 2, followed by the static method callMe()printing 4 twice, and ending with the main() method printing 5.

11. C. The Locale class has a constructor taking a language code and an optional countrycode. The Properties class is a type of Map so it also has a constructor. By contrast, aResourceBundle subclass is typically obtained by calling theResourceBundle.getBundle() method. ResourceBundle is an abstract class, so asubclass will get returned like ListResourceBundle.

12. E. Option C is clearly incorrect because the class has a public constructor so cannot bea singleton. Options A, B, and D are also incorrect because the height instance variableis not private. This means other classes in the same package can read and change thevalue. Therefore, Option E is correct.

13. E. The readObject() method returns an Object instance, which must be explicitly castto Cruise in the second try-with-resources statement. For this reason, the code doesnot compile, and Option E is the correct answer. If the explicit cast was added, thecode would compile but throw a NotSerializableException at runtime, since Cruisedoes not implement the Serializable interface. If both of these issues were corrected,the code would run and print 4,null. The schedule variable is marked transient, so itdefaults to null when deserialized, while numPassengers is assigned the value it hadwhen it was serialized. Note that on deserialization, the constructors and instanceinitializers are not executed.

14. B. Driver, Connection, Statement, and ResultSet are the four key interfaces you needto know for JDBC. DriverManager is a class rather than an interface. Query is not usedin JDBC. Since only Driver and ResultSet are interfaces in the list, Option B is theanswer.

15. A, C, F. The IntUnaryOperator takes an int value and returns an int value. Options Band E are incorrect because the parameter types, Integer and long, respectively, arenot compatible. Option B is incorrect because while unboxing can be used forexpressions, it cannot be used for parameter matching. Option E is incorrect becauseconverting from long to int requires an explicit cast. Option D is incorrect becausedividing an int by a double value 3.1 results in q/3.1 being a double value, whichcannot be converted to int without an explicit cast. The rest of the lambda expressionsare valid since they correctly take an int value and return an int value.

16. D, F. To begin with, the read() method of both classes returns an int value, makingOption A incorrect. As you may recall from your studies, neither use byte or char, sothat -1 can be returned when the end of the stream is reached without using anexisting byte or char value. Option B is incorrect because neither contain a flush()method, while Option C is incorrect because they both contain a skip() method. BothInputStream and Reader are abstract classes, not interfaces, making Option D correctand Option E incorrect. That leaves Option F as a correct answer. Both can be used toread character or String data, although Reader is strongly recommended, given itsbuilt-in support for character encodings.

17. B. There are not minus() or plus() methods on ChronoUnit making Options C, D, Eand F incorrect. Both Options A and B compile; however, they differ in the output.Option A prints 1 because you can add 1 to get from November to December. Option Bprints -1 because the first date is larger, and therefore Option B is the correct answer.

18. D. The code compiles without issue, making the first statement true and eliminatingOption B. It is possible that System.console() could return null, leading to aNullPointerException at runtime and making the third statement true. For thisreason, Options A and C are also incorrect. That leaves us with two choices. While theprocess correctly clears the password from the char array in memory, it adds the valueto the JVM string pool when it is converted to a String. The whole point of using achar array is to prevent the password from entering the JVM string pool, where it can

exist after the method that called it has finished running. For this reason, the secondstatement is false, making Option D correct and Option E incorrect.

19. B. Options C and D are incorrect because they print the Runner object rather than theint value it contains since peek() is called before mapping the value. The Runnerobject is something like Runner@6d03e736. Option A is incorrect because the map()method returns a Stream<Integer>. While Stream<Integer> does have a max() method,it requires a Comparator. By contrast, Option B uses mapToInt(), which returns anIntStream and does have a max() method that does not take any parameters. Option Bis the only one that compiles and outputs the int values.

20. E. The code does not compile, so Options A, B, and F are incorrect. The firstcompilation error is on line 3, which is missing a required semicolon (;) at the end ofthe line. A semicolon (;) is required at the end of any enum value list if the enumcontains anything after the list, such as a method or constructor. The next compilationerror is on line 4 because enum constructors cannot be public. The last compilationerror is on line 10. The case statement must use an enum value, such as FALL, not anint value. For these three reasons, Option E is the correct answer.

21. A, C, E. To start with, bustNow() now takes a Double value, while bustLater() takes adouble value. To be compatible, the lambda expression has to be able to handle bothdata types. Option A is correct, since the method reference System.out::printmatches overloaded methods that can take double or a Double (via unboxing). OptionB is incorrect, since intValue() works for the Consumer<Double>, which takes Double,but not DoubleConsumer, which takes double. For a similar reason, Option D is alsoincorrect because only the primitive double is compatible with this expression. OptionC is correct and results in just a blank line being printed. Option E is correct since it isjust the lambda version of the method reference in Option A. Finally, Option F isincorrect because of incompatible data types. The method reference is being usedinside of a lambda expression, which would only be allowed if the functional interfacereturned another functional interface reference.

22. F. This class correctly creates and retrieves a Java class resource bundle. Since count isan int, it is autoboxed into an Integer. However, rb.getString() cannot be called foran Integer value. The code throws a ClassCastException, so Option F is the answer. Ifthis was fixed, the answer would be Option C because the pre-increment is used andgetContents() is only called once.

23. C. The Java 8 date/time APIs count months starting with one rather than zero. Thismeans localDate is created as October 5, 2017. This is not the day that daylightsavings time ends. The loop increments the hour six times, making the final time07:00. Therefore Option C is the answer.

24. A. The code does not compile because BasicFileAttributes is used to read fileinformation, not write it, making Option A the correct answer. If the code was changedto pass BasicFileAttributeView.class to the Files.getFileAttributeView() method,then the code would compile, and Option B would be the correct answer. Finally,

remember that by default, symbolic links are not traversed by the Files.walk()method, avoiding a cycle. If FileVisitOption.FOLLOW_LINKS was passed, then the classwould throw an exception because Files.walk() does keep track of the files it visitsand throws a FileSystemLoopException in the presence of a cycle.

25. B. The code compiles without issue, making Option E incorrect. Option A is incorrectbecause it disables all assertions, which is the default JVM behavior. Option B is thecorrect answer. It disables assertions everywhere but enables them within the Watchclass, triggering an AssertionError at runtime within the checkHour() method. OptionC is incorrect because it enables assertions everywhere but disables them within theWatch class. Option D is also incorrect because -enableassert is not a valid JVM flag.The only valid flags to enable assertions are -ea and -enableassertions.

26. F. The code compiles without issue, making Option C incorrect. The main() methodcreates a thread pool of four threads. It then submits 10 tasks to it. At any given time,the ExecutorService has up to four threads active, which is the same number ofthreads required to reach the CyclicBarrier limit. Therefore, the barrier limit isreached twice, printing Jump! twice, making Option A incorrect. Unfortunately, theprogram does not terminate, so Option B is also incorrect. While eight of the taskshave been completed, two are left running. Since no more tasks will call the await()method, the CyclicBarrier limit is never reached, and the two remaining threads’tasks hang indefinitely. For this reason, Option F is the correct answer. Option E isincorrect because making the IntStream parallel would not change the result. OptionD is incorrect because the result is the same no matter how many times the programis executed.

27. C. The code does not compile because Files.isSameFile() requires Path instances,not String values. For this reason, Option C is the correct answer. If Path values hadbeen used, then the code would compile and print Same!, and Option A would be thecorrect answer since the isSameFile() method does follow symbolic links.

28. D, E. Since JavaProgrammerCert is a subclass of Exam, it cannot have a more specificvisibility modifier. Exam uses protected, which is broader than package-private inJavaProgrammerCert. This rules out Options A, B, and C. The other three options allcompile. However, Option F has a problem. Suppose your JavaProgrammerCert objecthas an Exam object with pass set to true for both the oca and ocp variables. Theimplementation in Option F doesn’t look at either of those variables. It looks at thesuperclass’s pass value. This isn’t logically correct. Therefore, Options D and E arecorrect.

29. B, D. First off, Option A is incorrect because a narrower exception can be thrown by anoverridden method, just not a broader checked exception. Option B is correct and isthe rule for return types of overridden methods. Option C is incorrect becauseoverridden methods must use the same input arguments. If the input arguments aredifferent, the method is overloaded, not overridden. Option D is correct becausemodifiers that limit the access of the inherited method are not permitted. Option E is

incorrect because private and static methods cannot be overridden. Remember thatprivate methods defined in parent classes are not inherited, aka not visible in thechild class, while static methods may be visible but cannot be overridden since theydo not belong to an instance. Finally, Option F is also incorrect. The @Overrideannotation is optional and recommended but not required.

30. D. The most common approach is III, which works for any SELECT statement that hasan int in the first column. If the SELECT statement has a function like count(*) orsum(*) in the first column, there will always be a row in the ResultSet, so II works aswell. Therefore, Option D is the answer.

31. E. DoubleBinaryOperator takes two double values and returns a double value.LongToIntFunction takes one long value and returns an int value. ToLongBiFunctiontakes two generic arguments and returns a long value. IntSupplier does not take anyvalues and returns an int value. ObjLongConsumer takes one generic and one longvalue and does not return a value. For these reasons, Option E is the correct answer.

32. F. While an Instant represents a specific moment in time using GMT, Java onlyallows adding or removing units of DAYS or smaller. This code throws anUnsupportedTemporalTypeException because of the attempt to add YEARS. Therefore,Option F is correct.

33. B. First we create two Blankie objects. One of them has the color pink and the otherleaves it as the default value of null. When the stream intermediate operation runs, itcalls the isPink() method twice, returning true and false respectively. Only the firstone goes on to the terminal operation and is printed, making Option B correct.

34. F. This class is not immutable. Most obviously, an immutable class can’t have a settermethod. It also can’t have a package-private instance variable. The getter methodshould be final so the class prevents a subclass from overriding the method. Since allthree of these changes are needed to make this class immutable, Option F is theanswer.

35. B, C, E. First of all, BufferedFileOutputStream does not exist in java.io, makingOption A incorrect. Also, OutputStream is abstract, not concrete, so Option F can alsobe eliminated. The data being written is stored in memory as a Student object, soserializing with ObjectOutputStream is appropriate. Since a large set of records areinvolved, we should use BufferedOutputStream. Since the data is being written to afile, we would use FileOutputStream. For these reasons, Options B, C, and E arecorrect. Note that FileWriter is not possible since it cannot be chained with the othertwo java.io classes, making Option D incorrect.

36. C, D. Option A is incorrect because the peek() method returns the next value or null ifthere isn’t one without changing the state of the queue. In this example, both peek()calls return 18. Option B is incorrect because the poll() method removes and returnsthe next value, returning null if there isn’t one. In this case, 18 and null are returned,respectively. Options C and D are correct because both the pop() and remove()

methods throw a NoSuchElementException when the queue is empty. This means bothreturn 18 for the first call and throw an exception for the second.

37. F. Line 11 assigns a relative Path value of ./song/../note to x. The second line assignsan absolute Path value of /dance/move.txt to y. Line 13 does not modify the value of xbecause Path is immutable and x is not reassigned to the new value. On line 14, theresolve() method is called using y as the input argument. If the parameter passed tothe resolve() method is absolute, then that value is returned, leading the firstprintln() method call to output /dance/move.txt. On the other hand, therelativize() method on line 15 requires both Path values to be absolute, or both to berelative. Mixing the two leads to an IllegalArgumentException on line 15 at runtimeand makes Option F the correct answer.

38. B. The code does not compile, so Option E is incorrect. The first compilation error is inthe try-with-resources declaration. There are two resources being declared, which isallowed, but they are separated by a comma (,) instead of a semicolon (;). The secondcompilation problem is that the order of exceptions in the two catch blocks arereversed. Since Exception will catch all StungException instances, the second catchblock is unreachable. For these two reasons, Option B is the correct answer.

39. C. The class compiles and runs without issue, so Options D and E are incorrect. Theresult of findSlow() is deterministic and always 1. The findFirst() method returnsthe first element in an ordered stream, whether it be serial or parallel. This makes it acostly operation for a parallel stream since the stream has to be accessed in a serialmanner. On the other hand, the result of findFast() is unknown until runtime. ThefindAny() method may return the first element or any element in the stream, even onserial streams. Since both 1 1 and 3 1 are possible outputs of this program, the answercannot be determined until runtime, and Option C is the correct answer.

40. D. There is not a method called getDefaultProperty() on the Properties class. Sincethe code does not compile, Option D is the answer. The getProperty() method onProperties is overloaded to allow passing a default value as the second parameter. Ifthis code was changed to use getProperty(), the answer would be Option C.

41. B, D. The try-with-resources statement requires resources that implementAutoCloseable. While Closeable extends AutoCloseable, it is certainly possible to havea class that implements AutoCloseable and works with try-with-resources but doesnot implement Closeable, making Option A incorrect. Option B is correct and a validstatement about how resources are closed in try-with-resources statements. Option Cis incorrect because the exception in the try block is reported to the caller, while theexception in the close() method is suppressed. Option D is the other correct answerbecause neither catch nor finally are required when try-with-resources is used.Lastly, Option E is incorrect. While the AutoCloseable does define a close() methodthat throws a checked exception, classes that implement this method are free to dropthe checked exception, per the rules of overriding methods.

42. B. The Roller class uses a formal type parameter named E with a constraint. The key

to this question is knowing that with generics, the extends keyword means anysubclass or the class can be used as the type parameter. This means both Wheel andCartWheel are OK. The wheel1 declaration is fine because the same type is used onboth sides of the declaration. The wheel2 declaration does not compile becausegenerics require the exact same type when not using wildcards. The wheel3 and wheel4declarations are both fine because this time there is an upper bound to specify that thetype can be a subclass. By contrast, the super keyword means it has to be that class ora superclass. The wheel6 declaration is OK, but the wheel5 one is a problem because ituses a subclass. Since wheel2 and wheel5 don’t compile, the answer is Option B.

43. B. This class is not a singleton because it needs a private constructor. Having a settermethod is fine. The state of a singleton’s instance variables is allowed to change. Thestatic initializer is fine as it runs at the same line as the declaration on line 2.Therefore, only the constructor addition is needed, and Option B is correct.

44. A. This code tries to update a cell in a ResultSet. However, it does not call updateRow()to actually apply the changes in the database. This means the SELECT query does notsee the changes and outputs the original value of 0. Option A is correct.

45. A, B, D. Option A is correct because the java.io stream classes implement Closeableand can be used with try-with-resources statements, while java.util.stream.Streamdoes not implement Closeable. Option B is correct since the Reader/Writer classes areused for handling character data. There are primitive stream classes injava.util.stream, but none for handling character data, such as CharStream. Option Cis incorrect because neither requires all data objects to implement Serializable.Option D is correct since flush() is found in Writer and OutputStream but not in anyof the java.util.stream classes. Option E is incorrect since both types of streamscontain a skip() method in some of their classes. Lastly, Option F is incorrect. Thereis no sort method found in any of the java.io classes. While there is a sorted()method in java.util.stream.Stream, the question is asking about what features areavailable in a java.io stream class and not in a java.util.stream.Stream class.

46. E. The code does contain compilation errors, so Option A is incorrect. The first is online 8. The readAllLines() method returns a List<String>, not a Stream. WhileparallelStream() is allowed on a Collection, parallel() is not. Next, line 14 does notcompile because of an invalid method call. The correct NIO.2 method call isFiles.isRegularFile(), not File.isRegularFile(), since the legacy File class doesnot have such a method. Line 18 contains a similar error. Path is an interface, not aclass, with the correct call being Paths.get(). Lastly, line 19 does not compile becausethe read() method throws Exception, which is not caught or handled by the main()method. For these four reasons, Option D is the correct answer.

47. D. The code compiles, making Option E incorrect. The key here is that theAtomicInteger variable is thread-safe regardless of the synchronization methods usedto access it. Therefore, synchronizing on an instance object, as in increment1() orincrement3(), or on the class object, as in increment2(), is unnecessary because the

AtomicInteger class is already thread-safe. For this reason, Option D is the correctanswer.

48. B, D. The Files.find() method requires a starting Path value, an int maximum depth,and a BiPredicate<Path,BasicFileAttributes> matcher instance. For these reasons,Options A, C, and E are incorrect. A FileVisitOption vararg is allowed but notrequired, making Option B correct. The other correct answer is Option D because themethod does not take a long value.

49. C, D. Option A is incorrect because Comparable is implemented on the class beingcompared. To be useful, such a class must have instance variables to compare, rulingout a lambda. By contrast, a Comparator is often implemented with a lambda. Option Bis incorrect because compare() is found in a Comparator. Option C is correct becausethese methods have different parameters but the same return type. Option D is correctbecause a Comparator doesn’t need to be implemented by the class being compared.Option E is incorrect because multiple comparators can use different orders forcomparison, which do not need to match the definition of equality.

50. C. The code compiles, so Option E is incorrect. The first boolean expression returnsfalse because the two Path expressions have different values and are therefore notequivalent. On the other hand, the second boolean expression returns true. If wenormalize t1, it becomes /stars.exe, which is equivalent to the t2 variable in terms ofequals(). The third boolean expression also returns true, even though the file doesnot exist. The isSameFile() method will avoid checking the file system if the two Pathexpressions are equivalent in terms of equals(), which from the second booleanexpression we know that they are. That leaves the fourth boolean expression, whichreturns true. Passing an absolute Path to resolve() just returns it, so t2 and t3 areequivalent values. For these reasons, Option C is the correct answer. Note that if thePath values had not been equivalent in terms of equals() for either of the last twoboolean expressions, then the file system would have been accessed, and since none ofthe files exist, an exception would have been thrown at runtime.

51. B, E. The method does not call the markSupported() prior to calling mark() andreset(). This is considered a poor practice. The input variable could be a subclass ofReader that does not support this functionality. In this situation, the method wouldignore the mark() call and throw an IOException on the reset() method, makingOption A incorrect and Option B correct. On the other hand, if marking the stream issupported, then no exception would be thrown. First, line 24 skips two values, 1 and 2.On line 25, the mark() method is called with a value of 5, which is the number ofcharacters that can be read and stored before the marked point is invalidated. Next,line 26 would skip another value but is undone by the reset() on line 27. The nextvalue to be read would be the third value, 3. The read(char[]) call would then read upto five values, since that is the size of the array. Since only four are left (4, 5, 6, 7) themethod would return a value of 4, corresponding to the number of characters readfrom the stream. For these reasons, the output is 3-4, making Option E the correct

answer. Options C and D can be eliminated because read() returns an int value, not achar.

52. C. The Function interface uses apply(), while the Consumer interface uses accept(),making Option C the correct answer. For reference, get() is the name of the methodused by Supplier, while test() is the name of the method used by Predicate.

53. D. The Teacher class, including all five assert statements, compiles without issue,making Option F incorrect. The first three assert statements on lines 4, 5, and 6evaluate to true, not triggering any exceptions, with choices updated to 11 after thefirst assertion is executed. Lines 4 and 7 demonstrate the very bad practice ofmodifying data in an assertion statement, which can trigger side effects. Regardless ofwhether an assertion error is thrown, turning on/off assertions potentially changesthe value returned by checkClasswork(). At line 7, the assertion statement 12==11evaluates to false, triggering an AssertionError and making Option D the correctanswer. The main() method catches and rethrows the AssertionError. Like writingassertion statements that include side effects, catching Error is also considered a badpractice. Note that line 8 also would trigger an AssertionError, but it is never reacheddue to the exception on line 7.

54. A, C, E. BooleanSupplier, DoubleUnaryOperator, and ToLongBiFunction are all validfunctional interfaces in java.util.function, making Options A, C, and E correct.Remember that BooleanSupplier is the only primitive functional interface in the APIthat does not use double, int, or long. For this reason, Option B is incorrect since charis not a supported primitive. Option D is incorrect because the functional interfacesthat use Object are abbreviated to Obj. The correct name for this functional interfaceis ObjIntConsumer. That leaves Option F, which is incorrect. There is no built-inPredicate interface that takes three values.

55. B, F. The LackOfInformationException class does not compile, making Option Aincorrect. The compiler inserts the default no-argument constructor intoInformationException since the class does not explicitly define any. SinceLackOfInformationException extends InformationException, the only constructoravailable in the parent class is the no-argument call to super(). For this reason, theconstructor defined at line t1 does not compile because it calls a nonexistent parentconstructor that takes a String value, and Option B is one of the correct answers. Theother two constructors at lines t2 and t3 compile without issue, making Options C andD incorrect. Option E is also incorrect. The getMessage() method is inherited, soapplying the @Override annotation is allowed by the compiler. Option F is the othercorrect answer. The LackOfInformationException is a checked exception because itinherits Exception but not RuntimeException.

56. C. First, a method reference uses two colons, so it should be Ready::getNumber.Second, you can’t use generics with a primitive, so it should be Supplier<Double>. Therest of the code is correct, so Option C is correct.

57. E. The class compiles, so Options A, B, and C are incorrect. It also does not produce an

exception at runtime, so Option F is incorrect. The question reduces to whether or notthe compute() method properly implements the fork/join framework in a multi-threaded manner. The compute() method returns "1" in the base case. In the recursivecase, it creates two PassButter tasks. In order to use multiple concurrent threads, thefirst task should be started asynchronously with fork(). While that is processing, thesecond task should be executed synchronously with compute() with the resultscombined using the join() method. That’s not what happens in this compute()method though. The first task is forked and then joined before the second task haseven started. The result is that the current thread waits for the first task to completelyfinish before starting and completing the second task synchronously. At runtime, thiswould result in single-threaded-like behavior. Since this is a poor implementation ofthe fork/join framework, Option E is the correct answer.

58. C. The filter() method passes two of the three elements of the stream through to theterminal operation. This is redundant since the terminal operation checks the samePredicate. There are two matches with the same value, so both anyMatch() andallMatch() return true, and Option C is correct.

59. E. First, Java looks for the requested resource bundle, which is AB_fr.class and thenAB_fr.properties. This rules out Options A, B, and C. Next, Java looks for the defaultlocale’s resource bundle, which is AB_en.properties. This rules out Option D. Javalooks for the default resource bundle. First, Java checks for a Java class file resourcebundle and then moves on to the property file. Therefore, Option F is incorrect, andOption E is the answer.

60. D. This code attempts to use two terminal operations, forEach() and count(). Onlyone terminal operation is allowed, so the code does not compile, and Option D iscorrect. The author of this code probably intended to use peek() instead of forEach().With this change, the answer would be Option A.

61. F. This code sets the default locale to Japanese and then tries to get a resource bundlefor container in the pod package. Since there is not a Japanese resource bundleavailable, it uses the default resource bundle pod.container.properties. Line r1successfully gets the value generic for the key name. Line r2 throws aMissingResourceException because there is not a key type in the default resourcebundle. The English resource bundle has this key, but it is not in the resource bundlehierarchy.

62. D. Line c1 correctly creates a stream containing two streams. Line c2 does not compilesince x is a stream, which does not have an isEmpty() method. Therefore, Option D iscorrect. If the filter() call was removed, flatMap() would correctly turn the streaminto one with four Integer elements and max() would correctly find the largest one.The Optional returned would contain 33, so Option B would be the answer in thatcase.

63. A, C. A Locale uses lowercase letters for language codes and uppercase letters forcountry codes. It can consist of only a language, making Option A correct. If both a

language and country code are present, the language code is first, making Option Ccorrect.

64. D, E. While this code does not close the Statement and Connection, it does compile,making Option A incorrect. Java defaults to auto-commit, which means the updatehappens right away, making Option C incorrect. Option B is incorrect because eitherexecute() or executeUpdate() is allowed for UPDATE SQL. The difference is the returntype. The execute() method returns a boolean while the executeUpdate() methodreturns an int. The code also runs without error, making Options D and E the answer.And remember to always close your resources in real code to avoid a resource leak.

65. F. This is tricky. The equals() method in the Object class has a parameter of typeObject. An overridden version is required to have the same type. The equals() methodin Sticker is an overload rather than an override. Since there is an @Overrideannotation, the code does not compile.

66. C. The code does not compile, so Options A and B are incorrect. The code does notcompile because the Sweater class is an inner class defined on the instance, whichmeans it is only accessible to be extended and used inside an instance method or by astatic method that has access to an instance of Wardrobe. Since dress() is a staticmethod, the declaration of local inner class Jacket does not compile on line v1,making Option C the correct answer. The rest of the code, including the abstract classTShirt and anonymous inner class defined inside dress(), compile without issue. Ifthe dress() method was updated to remove the static modifier, then the code wouldcompile and print Starting...Insulation:20 at runtime, making Option A the correctanswer.

67. E. The first statement is not true because Function takes two generic arguments andone input argument. If BiFunction was used instead of Function on line 7, then thecode would compile correctly. The second statement is also not true becauseIntSupplier does not take any generic arguments. The third statement is not true aswell, since Armor is an inner instance class. Without an instance of Sword in the staticmain() method, the call new Armor() on line 11 does not compile. For these reasons, allthree statements are not true, making Option E the correct answer.

68. B, F. A deadlock and livelock both result in threads that cannot complete a task, butonly in a livelock do the threads appear active, making Option A incorrect and OptionB correct. Options C and D are incorrect because they do not apply to thread liveness.A race condition is an unexpected result when two threads, which should be runsequentially, are run at the same time, leading to an unexpected result, making OptionE incorrect. Last but not least, starvation is caused by a single active thread that isperpetually denied access to a shared resource or lock, making Option F the othercorrect answer.

69. A, E. The first step is to convert both to GMT. We subtract the time zone offset to dothis. In GMT, the Nairobi time is 14:00, which we get by subtracting 3 from 17. ThePanama time is 15:00 because subtracting negative five from 10 gives us 15.

Remember that subtracting a negative number is like adding a positive number. Sincethe Nairobi time is an hour before the Panama time, Options A and E are correct.

70. D. This code actually does compile. Line c1 is fine because the method uses the ?wildcard, which allows any collection. Line c2 is a standard method declaration. Linec3 looks odd, but it does work. The lambda takes one parameter and does nothing withit. Since there is no output, Option D is correct.

71. A, C. JDBC 3.0 drivers require a Class.forName() call. Since this is missing, Option Ais correct, and Option B is incorrect. The Connection and Statement creation arecorrect, making Options E and F incorrect. Since the call to stmt.close() should bebefore the call to conn.close(), Option C is correct, and Option D is incorrect.

72. B. The code does not compile, so Options D and E are incorrect. The first compilationerror is in the Finder interface declaration. Since all interfaces are implicitly abstract,they cannot be marked final. The second compilation error is the declaration of thefind() method in the Waldo class. Since find() is inherited from the Finder interface,it is implicitly public. This makes the override of the method in Finder invalidbecause the lack of access modifier indicates package-level access. Since package-levelaccess is more restrictive than the inherited method’s access modifier, the overriddenmethod does not compile in the Waldo class. For these two reasons, Option B is thecorrect answer.

73. F. When summing int primitives, the return type is also an int. Since a long is larger,you can assign the result to it, so line 7 is correct. All the primitive stream types uselong as the return type for count(). Therefore, the code compiles, and Option E isincorrect. When actually running the code, line 8 throws an IllegalStateExceptionbecause the stream has already been used. Both sum() and count() are terminaloperations and only one terminal operation is allowed on the same stream. Therefore,Option F is the answer.

74. D. Line 34 does not compile because of an assignment and value mismatch. The r1variable is a Runnable expression. While there is an ExecutorService.submit() thattakes a Runnable expression, it returns Future<?> since the return type is void. Thistype is incompatible with the Future<Stream> assignment without an explicit cast,leading to a compiler error. Next, line 39 does not compile. The parallelStream()method is found in the Collection interface, not the Stream interface. Due to thesetwo compilation errors, Option D is the correct answer.

75. F. Internationalization means the program is designed so it can be adapted formultiple languages. Localization means the program actually supports multiplelocales. Since a localized application must first be internationalized, Option F is theanswer. Extracted is not a word commonly used with respect to handling multiplelanguages.

76. C. The class compiles, making Option E incorrect. If /woods/forest exists, then thefirst branch of the if-then statement executes, printing true at runtime. On the other

hand, if /woods/forest does not exist, the program will print true if /woods exists andfalse if /woods does not exist. Unlike mkdirs(), which if used would always returntrue in this case, mkdir() will return false if part of the parent path is missing. Forthis reason, Option C is correct, and Options A and B are incorrect. Finally, Option D isincorrect. This code is not expected to throw an exception at runtime. If the path couldnot be created, the mkdir() method just returns false.

77. D. Line 15 calls the method on line 9 since it is a Watch object. Line 16 is a SmartWatchobject. However, the getName() method is not overridden in SmartWatch since themethod signature is different. Therefore, the method on line 9 gets called again. Thatmethod calls getType(). Since this is a private method, it is not overridden and watchis printed twice. Option D is correct.

78. B. This code runs the loop six times, adding an hour to z each time. However, the firsttime is the repeated hour from daylight savings time. The time zone offset changes,but not the hour. This means the hour only increments five times. Adding that to01:00 gives us 06:00 and makes Option B correct.

79. C. Both schedule method calls do not compile because these methods are onlyavailable in the ScheduledExecutorService interface, not the ExecutorServiceinterface. Even if the correct reference type for service was used, along with acompatible Executors factory method, the scheduleWithFixedDelay() call would stillnot compile because it only contains a single numeric value. This method requires twolong values, one for the initial delay and one for the period. The execute() method callcompiles without issue because this method is available in the ExecutorServiceinterface. For these reasons, only the third statement is true, making Option C thecorrect answer.

80. A, D, E. Any class that inherits from RuntimeException or Error is unchecked, whileany class that does not is unchecked and must be declared or handled. AssertionErrorinherits from Error, while IllegalArgumentException and MissingResourceExceptioninherit from RuntimeException. The remaining classes—NotSerializableException,SQLException, and ParseException—each inherit Exception but not RuntimeException,making Options A, D, and E the correct answers.

81. C, D. To be a valid functional interface, an interface must declare exactly oneabstract method. Option A is incorrect, because CanClimb does not contain anyabstract methods. Next, all interface methods not marked default or static areassumed to be abstract, and abstract methods cannot have a body. For this reason,CanDance does not compile, making Option B incorrect. Options C and D are correctanswers because each contains exactly one abstract method. Option E is incorrectbecause it contains two abstract methods, since test() is assumed to be abstract.

82. A. A JDBC URL has three components separated by colons. None of these options usesthe correct colon delimiter, making Option A the correct answer. If all the semicolonswere changed to colons, Option D would be correct. I and V would still be incorrectbecause they don’t begin with the JDBC protocol and magic driver name as the first

two components.

83. F. The collector tries to use the number of characters in each stream element as thekey in a map. This works fine for the first two elements, speak and bark, because theyare of length 5 and 4, respectively. When it gets to meow, we have a problem becausethe length 4 is already used. Java requires a merge function be passed to toMap() as athird parameter if there are duplicate keys so it knows what to do. Since this is notsupplied, the code throws an IllegalStateException due to the duplicate key, andOption F is correct.

84. D. The application does not compile, so Options A, B, and C are incorrect. The one andonly compilation issue is that the ElectricBass class implements two interfaces thatdeclare default methods with the same getVolume() signature. A class can inherit twodefault methods with the same signature but only if the class overrides the methodswith its own version. Since ElectricBass does not override the method, theElectricBass class does not compile. Since this is the only compilation issue, OptionD is the correct answer. If the ElectricBass class did correctly override thegetVolume() method, the rest of the code would compile without issue. In this case,there would be nothing printed at runtime. The main() method just declares a localinner class but does not create an instance of it, nor does it call any method on it,making Option C the correct answer.

85. A, B, C. Files.find() and Files.list() return a Stream<Path>, while Files.lines()returns a Stream<String>. For these reasons, Options A, B, and C are the correctanswers. The NIO.2 Files class does not contain a listFiles() method, makingOption D incorrect. There is a method named listFiles() in the java.io.File class,but it returns a File array. Option E is also incorrect because theFiles.readAllLines() method returns a List<String>. Lastly, Option F is incorrectbecause Files.walkFileTree() uses a FileVisitor and returns a Path. If you were notfamiliar with the walkFileTree() method, then you could have ruled it out by knowingthe signatures for Options A, B, and C.

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OCA / OCP Practice Tests: Exam 1Z0-808 and Exam 1Z0-809

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